Question

How can you do the factorising part

Answer 1

$25a {}^{2} -9b²+12bc - 4c² \\ \\ = 25 {a}^{2} - (9 {b}^{2} - 12bc + 4 {c}^{2} ) \\ \\25 {a}^{2} - \{ {(3b)}^{2} - 2.3b.2c + (2c {)}^{2} \}\\ \\ = 25 {a}^{2} - (3b - 2c) {}^{2} \\ \\ = (5a+3b-2c)(5a - 3b + 2c)$

Formula Used:

x²-2xy+y²= (x-y)²

x²-y²= (x+y)(x-y)