x-y=1 证明x2+y2+1/x2+1/y2大于等于17/2

x-y=1 证明x2+y2+1/x2+1/y2大于等于17/2 y=x+√(1-x2) y2=x2+(1-x2)+2x√(1-x2) 证明：x2+y2+1>2(x-y-1) 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 2010.09.已知x、y为实数,且(x2+y2)(x2+y2+1)=20,求x2+y2的值 已知实数x.y满足（x2+y2）（x2+y2-1）=2,求x2+y2的值 X2y2-x2-y2+1 =x2(y2-1)-(y2-1) =(y2-1)(x2-1) =(y+1)(y-1)(x+1)(x-1) 中的=x2(y2-1)-(y2-1) =(y2-1)(x2-1是怎么算出来的? 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+y2=1和x2+y2-4x+2y=4解这组方程, 因式分解x2+y2-xy-x-y+1 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, 已知x2+4y2+x2y2+1=6xy,则(x4-y4)/(2x2+xy-y2)*(2x-y)/(xy-y2)/(x2+y2/y)2= 先化简,再求值:2x2-y2+2y2-3x2-2y2+x,其中x=-1,y=2 1.(x-y)(x2+xy+y2) 2.求值x2(x-1)-x(x2+x-1),其中x=2分之一 lim(x,y)→(0,0)(1-cos(x2+y2))/(x2+y2)x2lim(x,y)→(0,0)(1-cos(x2+y2))/(x2+y2)x2y2 y=x+1 x2+y2=5 怎么解, x2+y2=1,求x+y的最小值 x2+y2+xy=1则x+y最大值