已知﹣x+3y=5,求5(x-3y)²-8(x-3y)-5的值.急拜托拜托
问题描述:
已知﹣x+3y=5,求5(x-3y)²-8(x-3y)-5的值.急拜托拜托
答
﹣x+3y=5
x-3y=-5
5(x-3y)²-8(x-3y)-5
=5x(-5)²-8x(-5)-5
=125+40-5
=160