Question 1185609
{{{25(a^2-4ab+4b^2)-4(a^2+2ab+b^2)}}}

{{{25a^2-100ab+100b^2-4a^2-8ab-4b^2}}}

{{{21a^2-108ab+96b^2}}}

{{{3(7a^2-36ab+32b^2)}}}

Different combinations could be tried for the quadratic factorization.

{{{3(7a-8b)(a-4b)}}}