1.

Factorise : x3 - 3x2+3x + 7(a) (x - 1)(x2 - 4x + 7)(b) (x + 1)(x2 - 4x + 7)(c) (x + 1)(x2 + 4x + 7)(d) (x + 1)(x2 + 4x + 7)

Answer»

(b) (x + 1)(x2 - 4x + 7)

x3 - 3x2 + 3x + 7

= x3 - 3x2 +3x - 1 + 8

= (x - 1)3 + (2)3

= (x - 1 + 2)[(x - 1)2 - (x - 1) x 2 + 4)]

= (x + 1)(x2 - 2x + 1 - 2x + 2 + 4)

= (x + 1)(x2 - 4x + 7)



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