已知x²y的值是2,则(5x²y+5xy-7x)-(4x²y+5xy-7x)的值为 A.二分之一 B.-2 C.2 D.4

问题描述:

已知x²y的值是2,则(5x²y+5xy-7x)-(4x²y+5xy-7x)的值为 A.二分之一 B.-2 C.2 D.4

(5x²y+5xy-7x)-(4x²y+5xy-7x)
=5x²y+5xy-7x-4x²y-5xy+7x
=x²y
=2
选C