(x-二分之一y-1)(x-二分之一y+1)-(x-二分之一-1)平方=(x-y/2 -1)(x-y/2+1)-(x-y/2-1)²=(x-y/2)²-1²-(x-y/2)²+2(x-y/2) -1=2(x-y/2) -2=2x-y-2x=1.5 y=0.9原式=3-0.9-2=3-2.9=0.1...你确定正确吗100%肯定