Chapter 6. QUADRATIC EQUATIONS
Optional Questions and Answers for Algebraic Expressions and Polynomials [1 Mark]
CHECK YOUR PROGRESS 3.1
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Long Questions and Answers for Algebraic Expressions and Polynomials [ 3 or 4 Mark]
CHECK YOUR PROGRESS 6.1
1. Which of the following equations are quadratic equations ?
(i) 3x2+ 5 = x3 + x (ii) 3x2+ 5x + 2 = 0
(iii) (5y+1) (3y-1) = y + 1 (iv) x2+1x+1=52
(v) 3x+2x2 = 5x-4
Solution: (i) 3x2+ 5 = x3 + x
⇒x3+x=3x2+5
⇒x3-3x2+x-5=0 is not a quadratic equation as x3-3x2+x-5
is not a quadratic polynomial.
(ii) 3x2+ 5x + 2 = 0 is a quadratic equation as 3x2+ 5x + 2
is a quadratic polynomial.
(iii) (5y+1) (3y-1) = y + 1
⇒15y2-5y+3y-1=y+1
⇒15y2-2y-1=y+1
⇒15y²-3y-2=0 is a quadratic equation as 15y²-3y-2
is a quadratic Polynomial.
(iv) x2+1x+1=52
⇒2x2+1=5x+1
⇒2x2+2=5x+5
⇒2x2-5x+2-5=0
⇒2x²-5x-3=0 is a quadratic equation as 2x²-5x-3
is a quadratic polynomial .
(v) 3x+2x2 = 5x-4
⇒2x2-5x+3x+4=0
⇒2x2-2x+4=0 is a quadratic equation as 2x2-2x+4
is a quadratic polynomial.
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