七年级下册数学书45页知识技能要过程（x-2）（x+2）-（x+1)(x-3) (ab+1)^2-(ab-1)^2 (2x-y)^2-4(x-y)(x+2y)
问题描述：
七年级下册数学书45页知识技能
要过程（x-2）（x+2）-（x+1)(x-3) (ab+1)^2-(ab-1)^2 (2x-y)^2-4(x-y)(x+2y)
答
x^2-4-[x^2-3x+x-3] deng yu x^2-4-x^2+3x-x+3 deng yu 2x-1 a^2b^2+1-[ a^2b^2-1] deng yu a^2b^2+1-a^2b^2+1 deng yu 2 4x^2-4xy+y^2-4[x^2+2xy-xy-2y^2] deng yu 4x^2-4xy+y^2-4x^2-8xy+4xy+8y^2 deng yu 9y^2-8xy
答
45页没有技能训练
答
x2-4-(x2-2x-3)=2x-1 a^2b^2+1-a^2b^2+1=2 4x^2-4xy+y^2-4x^2-8xy+4xy+8y^2=9y^2-8xy