Finding support for multivariate transformation

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SUMMARY

The discussion focuses on the joint transformation of random variables X and Y, specifically defining Z as XY² and W as Y. The support of the transformed variables (Z, W) is mathematically described as the region defined by the inequalities 0 < √Z < W < 1. The original joint probability density function (pdf) of X and Y is given as f(x,y) = 12xy(1 - y) for 0 < x < 1 and 0 < y < 1. The graphical representation of the support is characterized as a quadrant-like shape rather than a simple rectangular or triangular form.

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  • Understanding of joint probability density functions (pdf)
  • Familiarity with transformations of random variables
  • Knowledge of graphical representation of mathematical functions
  • Basic concepts of inequalities in two dimensions
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For the given joint pdf of X and Y $$f(x,y) = 12xy(1 - y); 0 < x < 1;
0 < y < 1$$
Let $Z = XY^2$ and $W = Y$ be a joint transformation of (X,Y)

Sketch the graph of the support of $(Z,W)$ and describe it
mathematically.

I'm not very sure how to describe (Z,W).
First, I draw the graph of the support of X and Y, which is a rectangular support.

Now I "map" each interval over to (Z,W).

For $x=0, 0<y<1, z=0, 0<w<1$

For $x=1, 0<y<1, 0<z<w^2, 0<w<1 $

For $y=0, 0<x<1, z=0, w=0$

For $y=1, 0<x<1, 0<z<1, w=1 $

I'm not quite sure how to describe (Z,W), this isn't rectangular neither is it triangular. I have drawn the graph of what I think is the support of (Z,W). How do I describe this quadrant-like support? $0<w<1, 0<z<1, \sqrt{z}<w<1$?
support.jpg
 
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After some figuring out, I determined that the description of the support is all as described in the graph drawn. $0 < \sqrt{z} < w < 1$
 

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