Let $x_1, \ x_2$ be independent random variables.
The probability density function $f(x_i)= 2x \ \ \ \ for \ \ \ \ 0<x_i < 1 $ and $f(x_i)=0 \ \ \ \text{otherwise}$
Then, the density function $f(x_1,x_2)=4x_1x_2$ for $0< x_1, x_2 < 1$
And Y is defined as $Y=X_1+X_2$
What is the distribution function $G(Y)$? Solve by using distribution function method(graph method)
What I did is as follows:
$G(Y)=P(Y \le y)= P( X_1+X_2 \le y)=\int \int f(x_1,x_2) dx_2 dx_1$
And I draw the plot of $Y=X_1+X_2$. But I'm stacking here. Please show me.