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WAEC Mathematics 2018 Paper

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Question : 24

Total: 50

Factorise completely the expression

(3x + 2)(1 - x)
(3x + 2)(2x + 1)
3 $(x + 2)^2$
3(x + 1)(1 - x)

Solution:

$(x + 2)^2$ - $(2x + 1)^2$

= $(x^2 + 4x + 4) - (4x^2 + 4x + 1)$

= $x^2$ + 4x + 4 - 4 $x^2$ - 4x - 1

= -3 $x^2$ + 3

= 3 - 3 $x^2$

= 3(1 - $x^2$ )

= 3(1 + x)(1 - x)

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