Question

Выражение (x-6y)(x+6y)+9(2y)2 (a++8b)-4(4b)2 -4(3a)2+(6a-5c)(6a+5c)

Answer 1

$1)(x-6y)(x+6y)+9(2y)2=x^2-36y^2+36y^2=x^2$
$2)(a+8b)(-a+8b)-4(4b)^2=-(a+8b)(a-8b)-64b^2=$$-a^2+64b^2-64b^2=-a^2$
$3)-4(3a)^2+(6a-5c)(6a+5c)=-36a^2+36a^2-25c^2=-25c^2$