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Question
Simplify : ( x - 6 )( x - 4 )( x + 2 )
Solution
Using identity : (x + a)(x + b)(x + c) = x3 + (a + b + c)x2 + (ab + bc + ca)x + abc
(x - 6)(x - 4)(x + 2)
= x3 + (-6 - 4 + 2)x2 + [-6 × (-4) + (-4) × 2 + 2 × (-6)]x + (-6) × (-4) × 2
= x3 - 8x2 + (24 - 8 - 12)x + 48
= x3 - 8x2 + 4x + 48
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