Plot3D[(x)^2+(y+2)^2 ,{x,-5,5},{y,-5,5},PlotRange->{-1,25}]

Plot3D[x+y,{x,-5,5},{y,-5,5}]

Plot3D[Sqrt[9-x^2-y^2],{x,-3,3},{y,-3,3}]

Plot3D[-(x^3+5y),{x,-3,3},{y,-3,3}]

Plot[{x^2-0^2, x^2-1^2, x^2-2^2, x^2-3^2},{x,-3,3},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->20]]

Plot[{x^2-0^2, x^2-(-1)^2, x^2-(-2)^2, x^2-(-3)^2},{x,-3,3},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->20]]

Plot[{0^2-y^2, 1^2-y^2, 2^2-y^2, 3^2-y^2},{y,-3,3},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->20]]

Plot[{0^2-y^2,(- 1)^2-y^2, (-2)^2-y^2, (-3)^2-y^2},{y,-3,3},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->20]]

Plot3D[x^2-y^2,{x,-3,3},{y,-3,3},PlotLegends->Automatic]

ContourPlot[{x^2-y^2==-4,x^2-y^2==-1,x^2-y^2==0,x^2-y^2==1,x^2-y^2==4},{x,-3,3},{y,-3,3},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->20]]

Plot3D[-Sqrt[5-x^2-y^2],{x,-3,3},{y,-3,3}]

Plot[{x^3+Sin[-Pi/2],x^3+Sin[-Pi/4],x^3+ Sin[0],x^3+Sin[Pi/4],x^3+Sin[Pi/2]},{x,-1.5,1.5},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->20]]

Plot[{(-2)^3 + Sin[y],(-1)^3 + Sin[y], 0^3 +Sin[y], 1^3 +Sin[y],2^3+Sin[y]},{y,-Pi,Pi},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->20]]

Plot3D[x^3+Sin[y],{x,-2,2},{y,-2Pi,2Pi}]

ContourPlot[{x^3+Sin[y]==-8,x^3+Sin[y]==-1,x^3+Sin[y]==0,x^3+Sin[y]==1,x^3+Sin[y]==8},{x,-3,3},{y,-2Pi,2Pi},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->20]]

f[x_,y_]:=25-x^2-y^2

ContourPlot[{ f[x,y]==24,f[x,y] ==20, f[x,y]==15, f[x,y]==10, f[x,y]==5},{x,-5,5},{y,-5,5},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->20]]

g[x_,y_]:=Sqrt[x^2+y^2]
ContourPlot[{g[x,y]==1,g[x,y]==2,g[x,y]==3,g[x,y]==4,g[x,y]==5},{x,-5,5},{y,-5,5},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->20]]

Plot3D[f[x,y],{x,-5,5},{y,-5,5},PlotRange->{0,25}]
Plot3D[g[x,y],{x,-5,5},{y,-5,5},PlotRange->{0,5}]

ContourPlot3D[{x^2+y^2+z^2==1,x^2+y^2+z^2==4,x^2+y^2+z^2==9},{x,-3,3},{y,-3,3},{z,-3,3}]

a=SphericalPlot3D[{1},{θ,0,Pi},{ϕ,0,4 Pi/2},PlotStyle->Directive[Blue,Opacity[0.7],Specularity[White,20]],Mesh->None,PlotPoints->40];

b=SphericalPlot3D[{2},{θ,0,Pi},{ϕ,0,3 Pi/2},PlotStyle->Directive[Red,Opacity[0.7],Specularity[White,20]],Mesh->{{0},{0},{0}},PlotPoints->40];

c=SphericalPlot3D[{3},{θ,0,Pi},{ϕ,0,3 Pi/2},PlotStyle->Directive[Green,Opacity[0.7],Specularity[White,20]],Mesh->{{0},{0},{0}},PlotPoints->40];

abc=Show[a,b,c,PlotRange->Automatic]

ContourPlot3D[{x^2+y^2==1,x^2+y^2==2,x^2+y^2==3,x^2+y^2==4},{x,-3,3},{y,-3,3},{z,-3,3}]

ContourPlot3D[{x+z==1,x+z==2,x+z==3,x+z==4},{x,-3,3},{y,-3,3},{z,-3,3}]

ContourPlot3D[{x^2+y^2-z^2==-2},{x,-3,3},{y,-3,3},{z,-3,3}]

ContourPlot[{2-x-2 y==-8,2-x-2 y==-6,2-x-2 y==-4,2-x-2 y==-2,2-x-2 y==0,2-x-2 y==2,2-x-2 y==4,2-x-2 y==6,2-x-2 y==8},{x,-5,5},{y,-5,5},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->20]]

Table[3-(x+1)/2==z,{z,-4,4}]

ContourPlot[{3+(1/2) (-1-x)==-4,3+(1/2) (-1-x)==-3,3+(1/2) (-1-x)==-2,3+(1/2) (-1-x)==-1,3+(1/2) (-1-x)==0,3+(1/2) (-1-x)==1,3+(1/2) (-1-x)==2,3+(1/2) (-1-x)==3,3+(1/2) (-1-x)==4},{x,-5,15},{y,-15,15},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->20]]

Plot3D[x^2y/(x^2+y^2),{x,-3,3},{y,-3,3}]

plot=Table[x^2 y/(x^2+y^2)==c,{c,-1,1,.1}]
ContourPlot[plot,{x,-3,3},{y,-3,3},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->16]]

Plot3D[x^2/(x^2+y^2),{x,-3,3},{y,-3,3}]

plot=Table[x^2 /(x^2+y^2)==c,{c,0,1,.1}]
ContourPlot[Evaluate[plot],{x,-3,3},{y,-3,3},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->16]]

Plot3D[x^2*y/(x^4+y^2),{x,-3,3},{y,-3,3}]

plot=Table[x^2 *y/(x^4+y^2)==c,{c,-1,1,.2}]
ContourPlot[Evaluate[plot],{x,-3,3},{y,-3,3},PlotLegends->"Expressions",LabelStyle->Directive[FontSize->16]]