Question

${a }^{2} + 4ab - 3 {a}^{2} b - 6ab {}^{2} + 4 {b}^{2}$
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Answer 1

$a^{2} +4ab-3a^{2} b-6ab^{2} +4b^{2} =a^{2} +4ab+4b^{2}-3ab(a+2b)=\\ \\ (a+2b)(a+2b)-3ab(a+2b)=(a+2b)(a+2b-3ab)$