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Question
Solve equation using factorisation method:
(x + 3)2 – 4(x + 3) – 5 = 0
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Solution
(x + 3)2 – 4(x + 3) – 5 = 0
Let x + 3 = y
Then y2 – 4y – 5 = 0
⇒ y2 – 5y + y – 5 = 0
⇒ y(y – 5) + 1(y – 5) = 0
⇒ (y – 5)(y + 1) = 0
If y – 5 = 0 or y + 1 = 0
Then y = 5 or y = –1
⇒ x + 3 = 5 or x + 3 = –1
⇒ x = 2 or x = – 4
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