Question: If the pair of linear equations : is consistent and dependent , then [2026 Standard]
(a) (b)
(c)
(d)
Solution: (d)
[A pair of linear equations which are equivalent has infinitely many distinct common solutions . Such a pair is called a dependent pair of linear equations in two variables. ]
Question: Equation of another line parallel to be line represented byis : [2026 Standard]
(a) (b)
(c)
(d)
Solution: (c).
We consider ,
]
Question: If (0,0) is the solution of the equation ,then the value of c is : [2026 Standard]
(a) 0 (b) 1 (c) – 1 (d) any real number
Solution: (b) 1 .
Here, x = 0 and y = 0
We have,
]
Question: For what value(s) of k does the system of equations kx + 2y = 3 and 2x + y = 5 have a unique solution ? [2026 Standard]
(a) a real number (b)
(c)
(d)
Solution: Given,
We have, ]
Question: If x = 1 and y = 2 is a solution of the pair of linear equations 2x – 3y + a = 0 and 2x + 3y – b = 0, then : [2025 Standard]
(A) a = 2b (B) 2a = b (C) a + 2b = 0 (D) 2a + b = 0
Solution: Given, x = 1 and y = 2 is a solution of the pair of linear equations 2x – 3y + a = 0 and 2x + 3y – b = 0 .
and
]
Question: The value of ‘p’ for which the equations and
has infinitely many solutions is : [2025 Standard]
(a) – 6 (b) 6 only (c) (d) Any real number except
.
Solution: (c) .
Given,
]
Question: If 2x + 3y = 15 and 3x + 2y = 25, then the value of x – y is : [2023 Standard]
(a) – 10 (b) 8 (c) 10 (d) – 8
Solution: (c) 10 .
[ Given,
From (i) , we get
]
Question: The value of ‘k’ for which the lines represented by the equations 3x + 5y = 2 and 9x + 15y = 2k coincide, is : [2024 Basic ]
(A) 3 (B) – 3 (C) 6 (D) – 6
Solution: (a) 3
[ Given, 3x + 5y = 2 and 9x + 15y = 2k
]
Question: The value of k, if (6,k) lies on the line represented by x – 3y + 6 = 0 , is [2023 Basic]
(a) – 4 (b) 12 (c) – 12 (d) 4
Solution: (d) 4
[ Here,
]
Question: The pair of linear equations has : [2023 basic]
(a) a unique solution (b) exactly two solutions (c) infinitely many solutions (d) no solution
Solution: (d) no solution
[ Given,
Here,
So, the pair of linear equations has no solution. ]
Question: Consider the following pairs of linear equations : [SEBA 2020]
(i) ;
(ii) ;
Choose the correct alternative :
(a) The pair in (i) has no solution, whereas the pair in (ii) has unique solution .
(b) The pair in (i) has infinitely many solutions, whereas the pair in (ii) has no solution .
(c) The pairs in (i) and (ii) have no solutions .
(d) The pair in (i) has no solution, whereas the pair in (ii) has infinitely many solutions .
Solution : (d) The pair in (i) has no solution, whereas the pair in (ii) has infinitely many solutions .
[ We have , ]
Question: If the point lies on the lines represented by both the equations
and
, then the lines is :
(a) intersecting (b) coincident (c) Parallel (d) None of these
Solution: (a) intersecting .
[ We have ,
Therefore, the lines are intersecting. ]
Question: The value of for which the pair of linear equations
and
represents parallel lines is :
(a) (b)
(c)
(d)
Solution: (a) .
[ We have,
]
Question: Consider the following pairs of linear equations :[SEBA 2019]
(i) ,
(ii) ,
Choose the correct alternative .
(a) The pairs in (i) and (ii) are consistent .
(b) The pairs in (i) and (ii) are inconsistent .
(c) The pair in (i) is inconsistent, whereas the pair in (ii) is consistent .
(d) The pair in (i) is consistent, whereas the pair in (ii) is inconsistent .
Solution: (d) The pair in (i) is consistent, whereas the pair in (ii) is inconsistent .
[ We have , ]
Question: If the lines and
are coincident , then the value of
is :
(a) (b)
(c) – 11 (d) – 7
Solution: (a)
[ We have , ]
Question: A pair of linear equations ;
is said to be inconsistent, if
(a) (b)
(c)
(d)
Solution: (a)
Question: The graph of is a line parallel to the -
(a) – axis (b)
– axis (c) both
– axis and
– axis (d) none of these
Solution: (b) – axis .
Question: The pair of linear equations and
is : [CBSE 2020 standard]
(a) consistent (b) inconsistent (c) consistent with one solution (d) consistent with many solutions
Solution: (b) inconsistent .
[ We have ,
and
]
Question: The graph of is a line :
(a) parallel to – axis (b) perpendicular to
– axis (c) parallel to
– axis (d) passing through the origin .
Solution: (d) passing through the origin .
[ If x = 0 , then y = 4 × 0 = 0 . So, the line passes through (0,0), the origin. ]
Question: The lines representing the linear equations and
are :
(a) intersect at a point (b) parallel (c) coincident (d) intersect at exactly two points .
Solution: (b) parallel .
[ We have , ]
Question: The pair of equations and
graphically represents lines which are :
(a) Coincident (b) parallel (c) intersecting at (3,4) (d) intersecting at (4,3)
Solution: (d) intersecting at (4 , 3) .
Question: If pair of linear equations is consistent , then the lines represented by them are :[CBSE 2020 (Basic)]
(a) always coincident (b) parallel (c) always intersecting (d) intersecting or coincident.
Solution: (d) intersecting or coincident.
Question: Which of the following pair of linear equations is intersect at a point ?
(a) ,
(b)
,
(c) ,
(d)
,
Solution: (d) ,
.
[ (a) ,
(b) ,
(c) ,
(d) ,
So, the pair of linear equations is intersect at a point . ]
Question: If in the equation , the value of
is 6, then the value of
will be
(a) 2 (b) 6 (c) – 2 (d) 4
Solution: (c) – 2
[ Given, y = 6 ; We have,
]
Question: The solution of the pair of linear equations and
are :
(a) (2 , 3) (b) (3 , 2) (c) (3 , – 2) (d) (2 , – 3)
Solution: (d) (2 , – 3)
[ We have,
and
{from (i)}
Putting in equation
, we get
]
Question: The value of for which the given pair of linear equations has infinitely many solutions is :
;
(a) 12 (b) – 12 (c) – 6 (d) 6
Solution: (a) 12
[ We have , and
From part and
part , we get
]
Question: The value of so that the point
,lie on the line represented by
.
(a) 2 (b) 6 (c) – 2 (d) – 6
Solution: (c) – 2
[ Here , ,
We have ,
]
Question: Solve for x and y : [ 2026 Standard]
Solution: We have,
and
From (i) we get,
Therefore,.
Question: Solve the following system of equations for x and y : [ 2026 Standard]
Solution: We have,
and
From (i) we get,
Therefore, .
Question: Solve the following pair of linear equations for x and y algebraically : x+2y = 9 and y – 2x = 2 . [2024 Basic]
Solution: We have,
And
[From (i)]
From (i) we get
Therefore, .
Question: Check whether the point (– 4 , 3) lies on both the lines represented by the linear equations x+y+1 = 0 and x – y = 1 . [2024 Basic]
Solution: Here,
We have,
LHS : RHS
So, the point (– 4 , 3) lies on the linear equations x+y+1 = 0 .
Again,
LHS : RHS
So, the point (– 4 , 3) is not lies on the linear equations x – y + 1 = 0 .
Question: Solve the following pair of linear equations : 2x – 3y – 17 = 0 and 4x + y – 13 = 0 [2024 Basic]
Solution: We have,
And
From (i) we get
Therefore, .
Question: Find the number of solutions of the following pair of linear equations : [CBSE 2009]
and
Solution: We have , and
Here , ,
,
,
,
,
Thus, the pairs of linear equations are infinitely many solutions .
Qustion: Write whether the following pair of linear equations is consistent or inconsistent :
and
Solution: We have , ;
Here , ,
, c1=6
,
,
,
Thus, the pairs of linear equations is consistent .
Question: Solve for and
( Using elimination method) :
;
Solution: We have ,
and
[ From (i)]
From we get ,
Therefore, x = 4 and y = 1 .
Question: Which of the following pairs of linear equations has unique solution , no solution , or infinitely many solutions ?
;
Solution: We have, and
Here , ,
,
,
,
,
Thus, the pairs of linear equations has infinitely many solutions .
Question: For what value of does the pair of equations given below has a unique solution ?
;
Solution: We have , and
Here , ,
,
,
,
,
Therefore, for all values of , except
, the given pair of equations will have a unique solution .
Question: The cost of 2 kg apples and 1 kg of grapes on a day was found to be Rs 320 . The cost of 4 kg apples and 2 kg grapes was found to be Rs 600. If cost of 1 kg of apples and 1kg of grapes is Rs x and Rs y respectively , represent the given situation algebraically as a system of equations and check whether the system so obtained is consistent or not . [2025 Standard]
Solution: Given, the cost of 1 kg of apples and 1kg of grapes is Rs x and Rs y respectively .
A/Q,
and
, which is a false statement.
Therefore, the pair of equations has no solution (inconsistent).
Question: Five years ago, Nuri was thrice as old as sonu . Ten years later, Nuri will be twice as old as Sonu . How old are Nuri and Sonu ?
Solution: Let and
be the age of Sonu and Nuri respectively .
Five years ago , the age of Sonu and Nuri will be and
years respectively .
And Ten years later , the age of Sonu and Nuri will be and
years respectively .
A/Q ,
and
[ From
]
From we get ,
Therefore , 20 years and 50 years are the age of Sonu and Nuri respectively .
Question: Solve : ;
and
hence find the value of
for which
.
Solution: We have ,
And
From we get
Therefore, the value of m is – 1 .
Question: In a ,
. Find the three angles .
Solution: Given,
and
In , we have
,
,
Question: The difference between two numbers is 26 and one number is three times the other . Find them.
Solution: Let and
be the two number .
A/Q ,
And
[ From
]
From we get ,
Therefore , the two numbers are 39 and 13 respectively .
Question: Half the perimeter of a rectangular garden, whose length is 4 m more than its width, is 36 m . Find the dimensions of the garden . [SEBA 2019]
Solution: Let and
(in metres) are the length and width of the rectangular garden respectively .
A/Q ,
And
[ From
]
From we get ,
Therefore, 20 m and 16 m are the length and width of the rectangular garden respectively .
Question: For what value of will the following pair of linear equations has infinitely many solutions :
;
Solution: We have , ;
Here , ,
,
,
,
,
From 1st part and 2nd part , we get
From 2nd part and 3rd part , we get
,
Therefore , the value of is 6 .
Question: If the sum of two positive numbers is 44 and one number is three times the other number, then find the numbers.
Solution : Let and
be the first and second numbers respectively .
AQ ,
and
Putting in equation
, we get
Therefore, the two positive number are 33 and 11 respectively .
Question: Solve : ;
[CBSE2011]
Solution: We have ,
and
Therefore, the value of and
are 3 and 2 respectively .
Question: Solve the following pair of equations by substitution method :
;
Solution: We have ,
and
Putting in equation
we get ,
Therefore , the solution are and
.
Question: Use elimination method to find all possible solution of the following pair of linear equations :
;
Solution: We have ,
and
, which is a false statement .
Therefore , the pair of linear equations has no solution .
Question: Given the linear equation , write another linear equation in these two variables such that the geometrical representation of the pair so formed is : (i) intersecting lines (ii) parallel lines
Solution: Given, the linear equation is
Here,
(i) For intersecting lines:
We consider,
Now,
So, the another linear equation is .
(ii) Given, the linear equation is
Here,
For parallel lines:
We consider,
Now,
So, the linear equation is .
Question: Graphically , find whether the following pair of equations has no solution, unique solution or infinitely many solutions :
;
Solution: We have ,
and
Equation and
are same . Hence , the lines represented by equation
and
are coincident .
Therefore , equation and
have infinitely many solutions.
Question: 5 pencils and 7 pens together cost Rs. 50 , whereas 7 pencils and 5 pens together cost Rs. 46 .Find the cost of one pencil and that of one pen . [SEBA 2020]
Solution: let and
be the cost of one pencil and one pen respectively .
A/Q ,
From we get ,
Therefore , the cost of one pencil and one pen are Rs. 3 and Rs. 5 respectively .
Question: A fraction becomes , when 1 is subtracted from the numerator and it becomes
, when 8 is added to its denominator. Find the fraction. [2026 Standard]
Solution: Let, x and y be the numerator and denominator of the fraction respectively.
The fraction
A/Q,
and
From (i) we get,
Therefore, the fraction
Question: The monthly incomes of two persons are in the ratio 9 : 7 and their monthly expenditures are in the ratio 4 : 3 . If each saved Rs 5000, express situation algebraically as a system of linear equations in two variables . Hence, find their respective monthly incomes . [2025 Standard]
Solution: Let, the incomes of the two person by Rs 9x and Rs 7x and their expenditures by Rs 4y and Rs 3y respectively.
A/Q,
and
From (i) we get
Therefore, the monthly incomes of the persons are Rs 9 × 5000 = Rs 45000 and Rs 7 × 5000 = Rs 35000 respectively.
Question: The monthly incomes of A and B are in the ratio 8 : 7 and their expenditures are in the ratio 19 : 16. If each saves Rs 2500 per month, find the monthly income of each. [2024 Standard]
Solution: Let 8 x and 7x be the monthly incomes of A and B and also 19y and 16y be the monthly expenditures of A and B .
For A :
For B :
From (i) we get,
Therefore, A's income
And B's income
Question: A lending library has a fixed charge for the first three days and an additional charge for each day thereafter. Sarita paid Rs 27 for a book kept for seven days, while Ravi paid Rs 24 for a book he kept for six days. Find the fixed charge and the charge for each extra day. [2024 Basic]
Solution: Let, and
be the fixed charge and the charges for each extra day .
A/Q ,
And
Putting the value of in equation
, we get
Therefore, the fixed charge is Rs. 15 and the charge for each extra day is Rs. 3 .
Question: If 217x + 131y = 913 and 131x + 217y = 827, then solve the equations for the values of x and y. [2023 Standard]
Solution: We have,
and
Therefore, the values of x = 3 and y = 2 .
Question: If the system of linear equations 2x + 3y = 7 and 2ax + (a + b)y = 28 have infinite number of solutions , then find the value of ‘a’ and ‘b’ . [2023 Standard]
Solution: Given,
Here ,
Therefore, the values are
Question: Jaya scored 40 marks in a test getting 3 marks for each correct answer and losing 1 Mark for each incorrect answer . Had 4 marks being awarded for each correct answer and 2 marks were deducted for each incorrect answer then Jaya again would have scored 40 marks . How many questions were there in the Test ? [2023 Standard]
Solution : Let and
are the number of correct answers and incorrect answers respectively .
A/Q,
and
Putting in equation
, we get
Therefore, the number of question in the test is 40 (20 + 20 = 40) .
Question: Yash scored 40 marks in a test, getting 3 marks for each right answer and losing 1 mark for each wrong answer . Had 4 marks been awarded for each correct answer and 2 marks been deducted for each incorrect answer, then Yash would have scored 50 marks . How many questions were there in the test ?
Solution : Let and
are the number of right answers and wrong answers respectively .
A/Q,
and
Putting in equation
, we get
Therefore, the number of question in the test is 20 (15+5 = 20) .
Question: The sum of the numerator and the denominator of a fraction is 4 more than twice the numerator . If the numerator and denominator are increased by 3, they are in the ratio 2 : 3 . Determine the fraction.
Solution: Let, x and y be the numerator and denominator of the fraction respectively.
The fraction
A/Q,
and
[ from (i)]
From (i) we get
So, the fraction is .
Question: For which values of and
does the following pair of linear equations have an infinitely number of solutions ?
;
Solution: We have,
Here,
Since, the pair of linear equation have an infinitely number of solutions .
So ,
and
From and
we get,
From , we get
Therefore, the value of is
and the value of
is
.
Question: A fraction becomes when 1 is subtracted from the numerator and it becomes
when 8 is a added to its denominator . Find the fraction . [CBSE 2020]
Solution : Let and
be the numerator and denominator of the fraction respectively .
So, the fraction .
A/Q,
and
Putting in equation
, we get
Therefore, the fraction is .
Question: A fraction becomes , if 2 is added to both the numerator and the denominator . If 3 is added to both the numerator and denominator it becomes
. Find the fraction . [ SEBA 2016 ,20]
Solution : Let, and
are the numerator and the denominator of the fraction respectively .
The fraction .
A/Q ,
and
Putting in equation
, we get
Required the fraction is .
Question: Solve for and
: [CBSE 2004 , 07C , 08]
;
Solution: We have,
and
Putting in equation
, we have
Therefore, the solutions are and
.
Question: In a competitive examination, one mark is awarded for each correct answer while mark is deducted for every wrong answer. Jayanti answered 120 questions and got 90 marks. How many questions did she answer correctly?
Solution: Let x and y be the number of correct answers and wrong answers respectively .
A/Q,
and
[From (i)]
From (i) we get
Jayanti answered 100 questions correctly.
Question: The taxi charges in a city consist of a fixed charge together with the charge for the distance covered . For a distance of 10 km , the charge paid is Rs. 105 and for a journey of 15 km, the charge paid is Rs. 155 . What are the fixed charges and the charge per km ? How much does a person have to pay for travelling a distance of 25 km ?
Solution: Let, and
be the fixed charge and the charge per km respectively .
A/Q,
and
Putting in equation
we get
Therefore, a person have to pay for travelling a distance of 25 km Rs. (
)
Rs.(
)
Rs.(
)
Rs.
Question: A two-digit number is obtained by either multiplying the sum of the digits by 8 and then subtracting 5 or by multiplying the difference of the digits by 16 and then adding 3. Find the number.
Solution: Let the ten’s and the unit’s digits in the number be x and y , respectively.
The number is
A/Q,
and
From (i) we get
Therefore, the number
Question: Draw the graphs of the equation and
. Determine the coordinate of the vertices of the triangle formed by these lines and the x-axis, and shaded the triangular region.
Solution: We have ,
|
|
– 1 |
0 |
1 |
|
|
0 |
1 |
2 |
and
|
|
4 |
0 |
2 |
|
|
0 |
6 |
3 |
Plot the points A( – 1,0) , B(0,1) , C(1,2) ,D(4,0) , E(0,6) and F(2,3) on graph paper, and join the points to form the lines PQ and RS as shown in figure . We get the shaded triangle AFD with vertices A(– 1, 0) , F(2,3) and D(4,0) .
Question: The area of a rectangle gets reduces by 9 square units, if its length is reduced by 5 units and breadth is increased by 3 units . If we increase length by 3 units and breadth by 2 units , the area increases by 67 square units . Find the dimensions of the rectangle . [SEBA 2015 , 18]
Solution: let, and
are the length and breadth of the rectangle respectively.
Therefore , the area of rectangle
A/Q ,
and
From , we get
Required the length and breadth are 17 unit and 9 unit respectively.
Question: Draw the graphs of the pair of linear equations x – y + 2 = 0 and 4x – y – 4 = 0. Calculate the area of the triangle formed by the lines so drawn and the x-axis.
Solution: We have,
|
|
– 2 |
0 |
2 |
|
|
0 |
2 |
4 |
and
|
|
0 |
1 |
2 |
|
|
– 4 |
0 |
4 |
Plot the points A (– 2 ,0), B (0 , 2), C (2 , 4) , D(0 , – 4) , E(1 , 0) and F(2, 4) on the graph paper and join them.
The triangle formed by these lines and the x- axis is ACE or AFE .
The vertices of this triangle are A (–2, 0), C (2, 4) and E (1, 0) .
Here, AE = 3 units , FM = 4 units .
.
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