x=0:0.001:8 y=x.^2/sqrt((1-x.^2).^2+(0.4*x).^2); plot(x,y)画出的图怎么不对啊

已知全集S={(x,y)|x^2+y^2 若集合S={(x,y)/x+y=0},T={(x,y)x-y=-2},则S交T= 请问S=max{2x+y , 已知X*X+Y*Y+6X-8Y+25=0 求（Y/X)+(X/Y)-2=? x*x+2x-y*y+6y-8=0,x+y不等于2,求x-y的值 S=(x+1/y)+(x^2+1/y^2)+.+(x^n+1/y^n) 因为x=y,所以2x=2y,所以2s-(x+y)=2y-(x+y),即x-y=y-x则(x-y)/(y-x)/(x-y)对不对 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 设实数x,y满足方程:x^2+y^2-8x-6y+21=0 （1）求S=2x-y的最大值与最小值（2）求T=x^2+y^2-10x+2y+26的（2）求T=x^2+y^2-10x+2y+26的最大值与最小值. 若实数x,y满足{x+y-2≥0 x≤4 y≥5 则s=x+y的最大值为? 已知x^2+y^2-8x+12y+52=0 ,求1/2x-1/x-y(x-y/2x-x^2+y^2) 已知x^2+y^2-8x+12y+52=0 ,求1/2x-1/x-y(x-y/2x-x^2+y^2) 计算∫s∫（x+y+z)dS.S:x^2+y^2+z^2=4,z>=0 |x|+|y|=3,s=2|x|+|y|,求s的最大值和最小值 已知集合S={y/y=2^x},集合T={x/ln(x-1) 已知实数x,y满足x^2+y^2+4y=0,则s=x^2+2y^2-4y的最小值步骤要详细 已知x.x+y.y+8x+6y+25=0,求代数式(x.x-4y.y)/(x.x+4xy+4y.y)-x/(x+2y)的值 x>0,y>0,xy=4,s=x/根号y+y/根号x取最小值是x为