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Question
Solve the following equation by factorisation :
x(x + 1) + (x + 2)(x + 3) = 42
Solution
x(x + 1) + (x + 2)(x + 3) = 42
⇒ 2x2 + 6x + 6 – 42 = 0
⇒ x2 + 3x – 18 = 0
⇒ x2 + 3x – 18 = 0 ..(Dividing by 2)
⇒ x2 + 6x – 3x – 18 = 0
⇒ x(x + 6) 3(x + 6) = 0
⇒ (x + 6)(x – 3) = 0
Either x + 6 = 0,
then x = –6
or
x – 3 = 0,
then x = 3
Hence x = –6, 3.
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