Question

Middle term factorisation

Answer 1

I think this will be helpful to you

Answer 2

$\tt\purple{Question : \: {99a}^{2} - 202ab + {99b}^{2} } \\ \tt{ {99a}^{2} - 121ab - 81ab + {99b}^{2} } \\ \tt{11a(9a - 11b) - 9b(9a - 11b)} \\ \tt{(11a - 9b)(9a - 11b) \: \bf \underline\purple{answer}}$