Contact us
Choose a category below so we can get back to you as quickly as possible.
∵lx+ 2l與ly +7l互為相反數 ∴|x+2|+|y+7|=0 ∵|x+2|≥0,|y+7|≥0 ∴x+2=0,x=-2 y+7=0,y=-7 ∴-x+y=2-7=-5.
We and our partners use cookies and other technologies to analyze traffic and optimize your experience. View more info and control your cookies settings at any time in our Cookies Policy.