已知-x+2y=5,则5(x-2y)^2 -8(x-2y)-5的值为( )
问题描述:
已知-x+2y=5,则5(x-2y)^2 -8(x-2y)-5的值为( )
A.80 B.-170 C.160 D.60
答
C.160
-x+2y=5
x-2y=-5
5(x-2y)^2 -8(x-2y)-5
=5*25-8*(-5)-5
=125+40-5
=165-5
=160