Question

Factorise: 21(a+b)²-m(a+b)​

Answer 1

Step-by-step explanation:

$21(a^{2} + {b}^{2} + 2ab) - m( {a }^{2} + {b}^{2} + 2ab) \\ 21a^{2} + 21{b}^{2} + 42ab - m{a }^{2} - m{b}^{2} - 2mab \\ {a }^{2}(21 - m) \: {b}^{2}(21 - m) \: 2ab(21 - m) \\ 2{a }^{3} {b}^{3}(21 - m)$

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