a与b互为相反数,c与d互为倒数a+b=0cd=1x=4(a-2)-(a-3b)=3a+3b-8=3*(a+b)-8=-8d=1/cy=c^2d+d^2-(d/c+c-1)=c+1/c^2-1/c^2-c+1=1(x+y)/4-(3x-5y)/8=(-8+1)/4-(-24-5)/8=-7/4+29/8=15/8^是什么意思次方的意思，c^2表示c的2次方