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