Question

СРОЧНО!
7) (a^2 +6ab)^2 - 81b^4

Answer 1

 $= (a{2} +6 ab - 9b^{2})*( a^{2}+6ab + 9b^{2} ) = (a^{2} + 6ab - 9b^{2} )*(a+3b)^{2}$