x=0:0.1:1; y=56.6915*x^3-87.1174*x^2+40.0070*x-0.09043; plot(x,y); 这个程序错了,请问怎么解决

设x大于1,y大于0,x^y+x^-y=2根号二,x^y-x^-y等于? 实数x,y满足{x-y+1>=0;y+1>=0;x+y+1 |x-y|+|y+1|=0化简 mathematica软件,已知y[x],Y=f1(x),X(x)=f2(x),如何plot Y[X]?y[x_] := x + 9.81/2*x*xk=1X[x] = x - k*y'[x]/(1 + (y'[x])^2)^0.5Y[x] = y[x] + k/(1 + (y'[x])^2)^0.5Plot[{y[x],Y[X],},{x,0,2}] x=0:0.1:1; y=56.6915*x^3-87.1174*x^2+40.0070*x-0.09043; plot(x,y); 这个程序错了,请问怎么解决 （x+y-5)*（x+y-5)+（x-y+3)=0 x*x-y*y 已知:3x-5y=0,求x/y,x-y/y,x-y/x 若实数x,y满足x-y+1》=0,x+y>=0,x 已知x,y满足约束条件：x-y+1>=0,x+y-2>=0,x 若实数x,y满足x-y+1>=0,x+y>=0,x 画出不等式组x+y>0,x=还有不等式（x-y)(x-y-1)= X>0 Y>0证1/x+1/y>=4/(x+y)X>0 Y>0 证1/x+1/y>=4/(x+y) x>0 y>0 x+y=1,4/X+9/y最小值x>0 y>0 x+y=1,求4/X+9/y最小值 若|x+y-1|+（x-y-2)²=0,求代数式（x+2y)(x-2y）-（2x-y)(-y-2x)的值. {4x-3y-10=0 3x-2y=0,{3x-4(x-y)=2 2x-3y=1,{2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 已知2x-y=0,求分式【1+（3*y*y*y/x*x*x-y*y*y）】/【1+（2y/x-y）】的值注：x*x*x-y*y*y=（x-y）*（x*x+xy+y*y） y'/y=1/x 已知x^2+y^2-8x+12y+52=0 ,求1/2x-1/x-y(x-y/2x-x^2+y^2)