Expansions-15

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In the expansion of (5 x - 3) (x + 2) 2  ; find the coefficients of x 2 and x (ii) constant term.

Solution :

(5 x - 3) (x + 2) 2 = (5 x - 3) (x 2 + 4 x + 4)

= 5 x 3 + 20 x 2 + 20 x - 3 x 2 - 12 x - 12 = 5 x 3 + 17 x 2 + 8 x - 12

(i) Coefficient of x 2 = 17 and coefficient of x = 8

(ii) Constant term = - 12

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