$\displaystyle f(x,y)=\left\{I can't figure out how to set this up. I have to show that c = 10, but every time I do it I get c = 5. What am I doing wrong:

\begin{array}{lr}

cx^2+y& 0\le x\le 1,0\le y\le 1,y\le x\\

0&elsewhere,

\end{array}

\right.$

$\displaystyle 1=\int_{0}^{1}\int_{0}^{x}x^2y \, dydx=\frac{c}{5}\Longrightarrow c=5$