Mathematics
Factorise the following:
x6 + 63x3 - 64
Factorisation
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Answer
x6 + 63x3 - 64 = x6 + 64x3 - x3 - 64
= x3(x3 + 64) - 1(x3 + 64)
= (x3 + 64)(x3 - 1)
= (x3 + 43)(x3 - 13)
We know that,
a3 + b3 = (a + b)(a2 + b2 - ab)
a3 - b3 = (a - b)(a2 + b2 + ab)
∴ (x3 + 43)(x3 - 13) = (x + 4)(x2 - 4.x + 42)(x - 1)(x2 + x.1 + 12)
= (x + 4)(x2 - 4x + 16)(x - 1)(x2 + x + 1).
Hence, x6 + 63x3 - 64 = (x + 4)(x2 - 4x + 16)(x - 1)(x2 + x + 1).
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