# Help with optimization

The rectangle located in the first quadrant and is basically inscribed under a decreasing curve.The lower left hand corner is at the origin and the upper right hand corner on the curve. the equation is y = 5-2x^2.Please find the width, height and area of the largest such rectangle.

Hint: If $(x,y)$ is the upper corner of the rectangle, you have $A=xy$. Substitute in your equation for $y$ to get $A$ as a function of $x$. Then take $\frac {dA}{dx}$ and set it to zero to get an equation in $x$.
• @MichaelRametta: what do you get for $\frac {dA}{dx}$? I get $x$ close to $+1$ and an area about 3 – Ross Millikan Mar 27 '13 at 1:43