已知-x+3y=5,求5(x-3y)²-8(x-3y)-5的值
问题描述:
已知-x+3y=5,求5(x-3y)²-8(x-3y)-5的值
答
由题意,得
x-3y=-5
所以
原式=5×(-5)²-8×(-5)-5
=125+40-5
=165-5
=160