求极限lim(x,y)→(0,0) [1-cos(x2+y2)]/[(x2+y2)e^x2y2]

请求：二元函数求极限lim (x2+y2 )1/2-sin(x2+y2 )1/2(x,y→0) (x2+y2 )3/2请 已知x2+4y2+x2y2-6xy+1=0,求 x4-y4/2x-y 乘 2xy-y2/xy-y2 除以（x2+y2/x 求极限lim X→∞ [1+ x2/2 -√(1+ x2)]/(cos x –e x2 )sin x2 亲 已知x2+y2-4x-10y+29=0求x2y2+2x3y2+x4y2的值 已知圆x2+y2-2x-2y+1=0求x2+y2的最大值 化简求值（2X2-2y2）-3（X2y2+X2）+3（X2y2+y2）,其中X=-1,y=2 已知xy/x+y=1/3,x2y2/x2+y2=1/5,求xy的值. 1.已知X2+Y2-4X-6Y+13=0,求Y2-X2的值 已知x2-4x+y2-6y+13=0求x2+y2的值? 若X2+Y2-2X-6Y+10=0 ,求（x2-y2)/xy的值 已知方程x2 +y2+4x-2y-4=0,求x2 +y2的最大值 求圆x2+y2+2x-6y+1=0与圆x2+y2+2y-..