初二数学题【。】

来源：百度知道 编辑：UC知道 时间：2024/09/21 04:35:14
计算下面的数学题，简便方法，可用｛完全平方｝｛平方差｝...
（1）(x+y)^-(x-y)^

（2）103^

（3）（x-y+2z)^

（1）(x+y)^2-(x-y)^2
=[(x+y)+(x-y)][(x+y)-(x-y)]
=(x+y+x-y)(x+y-x+y)
=2x*2y
=4xy

（2）103^
=(100+3)^2
=100^2+2*100*3+3^2
=10000+600+9
=10609

（3）（x-y+2z)^2
=[(x-y)+2z]^2
=(x-y)^2+4(x-y)z+4z^2
=x^2-2xy+y^2+4xz-4yz+4z^2

（1）(x+y)^-(x-y)^
=（x+y+x-y）(x+y-x+y)
=2x*2y
=4xy
（2）103^
=(100+3)^
=100^+600+9
=10609
（3）（x-y+2z)^
=[(x-y)+2z]^
=(x-y)^+4(x-y)z+4z^
=x^-2xy+y^+4xz-4yz+4z^

（1）(x+y)^2-(x-y)^2
=(x+y+x-y)(x+y-x+y)
=2x*2y
=4xy

（2）103^
=(100+3)^2
=100^2+2*100*3+3^2
=10000+600+9
=10609

（3）（x-y+2z)^2
=[(x-y)+2z]^2
=(x-y)^2+4(x-y)z+4z^2
=x^2-2xy+y^2+4xz-4yz+4z^2
OK?

一
(x+y)^-(x-y)^
=x^+2xy+y^-x^+2xy-y^
=4xy
二
103^
=(100+3)^
=100^+2*100*3+3^
=10000+600+9
=10609