(a+b)(a+b-6)+9
4x²y²-(x²+y²)²
(a+b)(a+b-6)+9
4x²y²-(x²+y²)²
(a+b)(a+b-6)+9
解答:(a+b)^2-6(a+b)+9
=[(a+b)-3]^2
=(a+b-3)^2
4x²y²-(x²+y²)²
解答: [2xy+(x^2+y^2)][2xy-(x^2+y^2)]
=(x^2+2xy+y^2)(-x^2+2xy-y^2)
=(x+y)^2*[-(x^2-2xy+y)]
=(x+y)^2[-(x-y)]^2
(a+b)(a+b-6)+9=(a+b)²-6(a+b)+9=(a+b-3)²
4x²y²-(x²+y²)²=(2xy+x²+y²)(2xy-x²-y²)=-(x+y)²(x-y)²
(a+b)(a+b-6)+9=(a+b-3)²
4x²y²-(x²+y²)²=(x²-y²)²
1.(a+b-3)的平方
2.—(X+Y)平方(X-Y)平方
1、 (a+b)(a+b-6)+9=(a+b)²-6(a+b)+3²=(a+b)²-2×(a+b)×3+3² =(a+b-3)²
2、 4x²y²-(x²+y²)²= (2xy)² -- (x²+y²)² =[(2xy+x²+y²)][(2xy-x²-y²)]=(x+y)²[--(x-y)²]= -- (x+y)²(x-y)²
谢谢采纳
(a+b)(a+b-6)+9=(a+b)²-6(a+b)+9=(a+b-3)²
4x²y²-(x²+y²)²=(2xy+x²+y²)(2xy-x²-y²)=-(x+y)²(x-y)²