证明：x2+y2+1>2(x-y-1)

证明：x2+y2+1>2(x-y-1) x-y=1 证明x2+y2+1/x2+1/y2大于等于17/2 已知x,y满足（x2+y2）(x2+y2-1)=2,则x2+y2的值为多少?x2,y2表示x和y的平方 已知x>0,y>0,x+y=1,求证x2+y2大于等于1//2 .证明：因为xy≤1/4,x2+y2≥2xy,所以x2+y2≥1/2有同学这样证,我认为不对, y=x+√(1-x2) y2=x2+(1-x2)+2x√(1-x2) 已知实数x.y满足（x2+y2）（x2+y2-1）=2,求x2+y2的值 2/1(x2-y)+3/1(x-y2)+6/1(x2+y2) x2+y2=1和x2+y2-4x+2y=4解这组方程, 先化简,再求值:2x2-y2+2y2-3x2-2y2+x,其中x=-1,y=2 已知x2+4y2+x2y2+1=6xy,则(x4-y4)/(2x2+xy-y2)*(2x-y)/(xy-y2)/(x2+y2/y)2= 因式分解x2+y2-xy-x-y+1 [2/xy/(1/x+1/y)2+(x2+y2)/(x2+2xy+y2)]*2x/(x-y) M=X2+Y2+1,N=X+Y+XY,证明M大于等于N.（ 2 是平方的意思) 已知x+y+z=xyz,证明：x(1-y2)(1-z2)+y(1-x2)(1-z2)+z(1-x2)(1-y2)=4xyz x2-2xy+y2-1/x-y-1 证明√X2+Y2+√(X-1)2+Y2+√X2+(Y-1)2+√(X-1)2+(Y-1)2>=2√2并求=成立时X与Y的值 2x2+xy-3y2+x+4y-1因式分解 3y2-x2+(2x-y)-2(x2+3y2),其中x=1,y=-2先化简,再求值.