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Question
Factorise the following.
y2 + 4y – 21
Sum
Solution
We have,
y2 + 4y – 21 = y2 + (7 – 3)y – 21
= y2 + 7y – 3y – 21
= y(y + 7) – 3(y + 7)
= (y + 7)(y – 3)
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Chapter 7: Algebraic Expression, Identities and Factorisation - Exercise [Page 235]
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