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Question
Solve the following quadratic equation by factorisation:
x2 + 3x - 18 = 0
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Solution
The given quadratic equation is
x2 + 3x - 18 = 0
⇒ x2 + 6x - 3x - 18 = 0
⇒ x(x + 6) -3(x + 6) = 0
⇒ (x + 6) (x - 3) = 0
when x + 6 = 0
x = -6
when x - 3 = 0
x = 3
∴ x = {-6, 3}.
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