若xy =-(√2),x-y=5(√2)-1,求xy-x+y-1的值
问题描述:
若xy =-(√2),x-y=5(√2)-1,求xy-x+y-1的值
快
答
xy-x+y-1
= xy-(x-y)-1
= -√2 - (5√2-1) - 1
=-√2 - 5√2 +1- 1
=-6√2