Question

${4x}^{2} - 8xy - {21y}^{2}$
Pls solve this​

Answer 1

$= 4 {x}^{2} - 8xy - 21 {y}^{2} \\ = 4 {x}^{2} - 14x y+ 6x y- 21 {y}^{2} \\ = 2x(2x + 3y) - 7y(2x + 3y) \\ = (2x - 7y)(2x + 3y)$