Question

Factorise : (a + b)2 - 14c(a + b) + 14c2​

Answer 1

Answer:

$put \: \: a + b = t \\ \\ = {t}^{2} - 14tc + 14 {c}^{2} \\ \\ = {t}^{2} - (7 + \sqrt{35} )tc - (7 - \sqrt{35})tc + 14 {c}^{2} \\ \\ = (t - (7 + \sqrt{35})c)(t - (7 - \sqrt{35}) c) \\ \\ =( a + b - 7c - \sqrt{35} c)(a + b - 7c + \sqrt{35} c)$