Mathematics
Factorize completely using factor theorem : 2x3 - x2 - 13x - 6.
Factorisation
ICSE 2023
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Answer
Substituting x = -2 in 2x3 - x2 - 13x - 6, we get :
⇒ 2(-2)3 - (-2)2 - 13(-2) - 6
⇒ 2(-8) - 4 + 26 - 6
⇒ -16 - 4 + 20
⇒ -20 + 20
⇒ 0.
∴ x + 2 is a factor of the polynomial 2x3 - x2 - 13x - 6.
Dividing, 2x3 - x2 - 13x - 6 by x + 2, we get :
∴ 2x3 - x2 - 13x - 6 = (x + 2)(2x2 - 5x - 3)
= (x + 2)(2x2 - 6x + x - 3)
= (x + 2)[2x(x - 3) + 1(x - 3)]
= (x + 2)(2x + 1)(x - 3).
Hence, 2x3 - x2 - 13x - 6 = (x + 2)(2x + 1)(x - 3).
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