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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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