Question

simplify
$(9xy + 2z )(9xy - 2z)$

Answer 1

Hey friend your answer is here
$(9xy + 2z)(9xy - 2z) \\ = ( {9xy})^{2} - ( {2z})^{2} \\ = 81 {x}^{2} {y}^{2} - 4 {z}^{2}$