Image of Set S Under Transformation | u^2 + v^2 <= 1

[magnifik]

find the image of the set S under the given transformation: S is the disk given by u^2 + v^2 <= 1 where x=au, y=bv

since it is a circle i have that the boundaries are [-1,1] x [-1.1] so for my equations i got
x = au, y = -b
x = a, y = bv
x = au, y = b
x = -a, y = bv

i don't know what the next step would be in trying to draw that

 

[Mark44]

If x = au and y = bv, then u = x/a and v = y/b. I would replace u and v by x/a and y/b, respectively, in the given inequality.