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GRE 9768 Question 48

Posted: Thu Oct 15, 2009 11:32 pm
by lizp
Hi, I'm having a hard time with this:

#48 Consider the change of variables from the xy-plane to the uv-plane given by the equations: u = x^(1/3) + y and v = 1 + y

Under this transformation, the image of the region (x,y): x element of [0,1], y element of [0,1] is which of the shaded regions?

Why is the answer not A?

Thanks

Re: GRE 9768 Question 48

Posted: Thu Oct 15, 2009 11:36 pm
by lizp
sorry i mean why is it not D?

Re: GRE 9768 Question 48

Posted: Fri Oct 16, 2009 12:18 am
by jl2886
Consider the square of side one in he xy-plane
parametrize the square:
x=t, y=0 t from 0 to 1
x=1, y=t t from 0 to 1
x=t, y=1 t from 1 to 0
x=0, y=t t from 1 to 0

The orientation doesn't really matter.

In any case sub in the above param. into change

u=t, v=1 t from 0 to 1
u=1+t v=1+t t from 0 to 1
u=t+1, v=2 t from 1 to 0
u=t, v=1+t t from 1 to 0

And that is choice A