已知-x+3y=5,则5(x-3y)2-8(x-3y)-5的值为( ) A.80 B.-170 C.160 D.60
问题描述:
已知-x+3y=5,则5(x-3y)2-8(x-3y)-5的值为( )
A. 80
B. -170
C. 160
D. 60
答
∵-x+3y=5,
∴x-3y=-5,
∴5(x-3y)2-8(x-3y)-5
=5×(-5)2-8×(-5)-5
=125+40-5
=160.
故选C.