Question

Упростите выражение:
1)(5x-7y)(5x+7y)+(7x-5y)(7x+5y)
2)(x+4)^2-(x-2)(x+2)
3)(8a-3b)(8a+3b)-(6a-5b)^2
4)(m-3)(m+4)-(m+2)^2+(4-m)(4+m)