已知X-3Y=0,求(2X+Y)(X-Y)/X的平方-2X+Y的平方的值.
问题描述:
已知X-3Y=0,求(2X+Y)(X-Y)/X的平方-2X+Y的平方的值.
已知X-3Y=0,求(2X+Y)(X-Y)/X^2-2X+Y^2的值得。
答
题目有误,改为“已知X-3Y=0,求(2X+Y)(X-Y)/(X^2-2XY+Y^2)的值
(2X+Y)(X-Y)/(X^2-2XY+Y^2)
=(2X+Y)(X-Y)/(X-Y)^2
=(2X+Y)/(X-Y)
已知X-3Y=0得X=3Y带入上式得:
(2X+Y)(X-Y)/(X^2-2XY+Y^2)
=(2X+Y)/(X-Y)
=(6Y+Y)/(3Y-Y)
=7/2