# Factorize Each of the Following Quadratic Polynomials by Using the Method of Completing the Square: Y2 − 7y + 12 Answer 9: - Mathematics

Sum

Factorize each of the following quadratic polynomials by using the method of completing the square:
y2 − 7y + 12

#### Solution

$y^2 - 7y + 12$
$= y^2 - 7y + \left( \frac{7}{2} \right)^2 - \left( \frac{7}{2} \right)^2 + 12 [\text{ Adding and subtracting }\left( \frac{7}{2} \right)^2 ]$
$= (y - \frac{7}{2} )^2 - \frac{49}{4} + \frac{48}{4} [\text{ Completing the square }]$
$= (y - \frac{7}{2} )^2 - \frac{1}{4}$
$= (y - \frac{7}{2} )^2 - \left( \frac{1}{2} \right)^2$
$= [(y - \frac{7}{2}) - \frac{1}{2}][(y - \frac{7}{2}) + \frac{1}{2}]$
$= (y - \frac{7}{2} - \frac{1}{2})(y - \frac{7}{2} + \frac{1}{2})$
$= (y - 4)(y - 3)$

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#### APPEARS IN

RD Sharma Class 8 Maths
Chapter 7 Factorization
Exercise 7.9 | Q 9 | Page 33