填空题:9(x+2y)^2-25(x-2y)^2=[ ]^2-[ ]^2
问题描述:
填空题:9(x+2y)^2-25(x-2y)^2=[ ]^2-[ ]^2
9(x+2y)^2-25(x-2y)^2=[ ]^2-[ ]^2
答
9(x+2y)^2-25(x-2y)^2=[ ]^2-[ ]^2=3^2(x+2y)^2-5^2(x-2y)^2=[3(x+2y)]^2-[5(x-2y)]^2 公式是(a^n)×(b^n)=(ab)^n=(3x+6y)^2-(5x-10y)^2∴9(x+2y)^2-25(x-2y)^2=[3x+6y]^2-[5x-10y]^2