var('x y z')
S1 =  line([(0,0,0), (4,0,0)],color="red")
S2 =  line([(0,0,0), (0,4,0)],color="red")
S3 =  line([(0,0,0), (0,0,4)],color="red")
S4 = implicit_plot3d(x^2 + z^2 == 9, (x, -3, 3), (y, -3, 3), (z, -4, 4), plotpoints=20, opacity=.5)
show(S1+S2+S3+S4, aspect_ratio=[1,1,1])


var('x y z')
S1 =  line([(0,0,0), (4,0,0)],color="red")
S2 =  line([(0,0,0), (0,4,0)],color="red")
S3 =  line([(0,0,0), (0,0,4)],color="red")
S4 = implicit_plot3d(y^2 + z^2 == 9, (x, -3, 3), (y, -3, 3), (z, -4, 4), plotpoints=20, opacity=.5)
show(S1+S2+S3+S4, aspect_ratio=[1,1,1])





var('x y z')
S1 =  line([(0,0,0), (4,0,0)],color="red")
S2 =  line([(0,0,0), (0,4,0)],color="red")
S3 =  line([(0,0,0), (0,0,4)],color="red")
S4 = implicit_plot3d(z == y^2 - x^2, (x, -3, 3), (y, -3, 3), (z, -4, 4), plotpoints=20, opacity=.5)
show(S1+S2+S3+S4, aspect_ratio=[1,1,1])



var('x y z')
S1 =  line([(0,0,0), (4,0,0)],color="red")
S2 =  line([(0,0,0), (0,4,0)],color="red")
S3 =  line([(0,0,0), (0,0,4)],color="red")
S4 = implicit_plot3d((x^2)/2 + y^2 - (z^2)/2 == 1, (x, -3, 3), (y, -3, 3), (z, -4, 4), plotpoints=20, opacity=.5)
show(S1+S2+S3+S4, aspect_ratio=[1,1,1])




var('x y z')
S1 =  line([(0,0,0), (4,0,0)],color="red")
S2 =  line([(0,0,0), (0,4,0)],color="red")
S3 =  line([(0,0,0), (0,0,4)],color="red")
S4 = implicit_plot3d(z == 4*x^2+y^2, (x, -3, 3), (y, -3, 3), (z, -4, 4), plotpoints=20, opacity=.5)
show(S1+S2+S3+S4, aspect_ratio=[1,1,1])




var('x y z')
S1 =  line([(0,0,0), (4,0,0)],color="red")
S2 =  line([(0,0,0), (0,4,0)],color="red")
S3 =  line([(0,0,0), (0,0,4)],color="red")
S4 = implicit_plot3d(x^2 +(y^2)/9 +(z^2)/4 == 1, (x, -3, 3), (y, -3, 3), (z, -4, 4), plotpoints=20, opacity=.5)
show(S1+S2+S3+S4, aspect_ratio=[1,1,1])



var('x y z')
S1 =  line([(0,0,0), (4,0,0)],color="red")
S2 =  line([(0,0,0), (0,4,0)],color="red")
S3 =  line([(0,0,0), (0,0,4)],color="red")
S4 = implicit_plot3d((y^2) + (x^2) == (z^2), (x, -3, 3), (y, -3, 3), (z, -4, 4), plotpoints=20, opacity=.5)
show(S1+S2+S3+S4, aspect_ratio=[1,1,1])





var('x y z')
S1 =  line([(0,0,0), (4,0,0)],color="red")
S2 =  line([(0,0,0), (0,4,0)],color="red")
S3 =  line([(0,0,0), (0,0,4)],color="red")
S4 = implicit_plot3d((x-1/2)^2 +(y^2) == 1, (x, -3, 3), (y, -3, 3), (z, -4, 4), plotpoints=20, opacity=.5)
S5 = implicit_plot3d((x)^2 +(y^2)+(z^2) == 1, (x, -3, 3), (y, -3, 3), (z, -4, 4), plotpoints=20, opacity=.5)
show(S1+S2+S3+S4+S5, aspect_ratio=[1,1,1])