Question

9(a+b)^2-25(a-b)^2

Answer 1

. 9(a-b)^2-25(a+b)^2
=[3(a+b)]^2-[5(a-b)]^2
=[3a+3b]^2-[5a-5b]^2
=[3a+3b+5a-5b][3a+3b-5a+5b]
=(8a-2b)(8b-2a)

Answer 2

9(a+b)^2-25(a-b)^2
=(3a+3b+5a-5b)(3a+3b-5a+5b)
=(8a-2b)(-2a+8b)
=-4(4a-b)(a-4b)

追问

(x^2-3)^2+12(3-x^2)+36 4m^2n^2-(m^2+n^2)^2