问题
选择题
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
答案
∵-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.
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
∵-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.