Question

Factorise: 16x²+40xy-81+25y²​

Answer 1

We have,

$\quad 16 {x}^{2} + 40xy - 81 + 25 {y}^{2} \\ \\ = (16 {x}^{2} + 40xy + 25 {y}^{2} ) - (81) \\ \\ = \left( {(4x)}^{2} + 2(4x)(5y) + {(5y)}^{2} \right) - (9 \times 9) \\ \\ = {(4x + 5y)}^{2} - {(9)}^{2} \\ \\ = (4x + 5y - 9)(4x + 5y + 9)$

Answer 2

Answer:

it's a doubt not boubt sister and thanks for answering my doubt