Question

factorise a3 - 27 b3 + 7 a square b - 21 a b square
please help me and answer this question ​

Answer 1

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a³-27b³+7a²b-21ab²

compared to a³+b³3a²b-3ab²

u get the answer

(a-3b)³=0

a=3b

b=a/3