# Need help with review question on test tomorow

1. Jun 10, 2004

### 2Pac

need help please. tonight if possible. I need to find the largest area of a rectangle with base on the x-axis and upper corners touch the parabola with the equation y=12-x^2
thanks

2. Jun 10, 2004

### AKG

Well, you know the rectangle will be symmetrical about the y-axis. That means, if it touches the parabola at x = -a, it will touch at x = a as well. The rectangle will have an area of $A = bh = (2x)(12 - x^2)$. Hopefully you see why this is. Now, it's simply a matter of finding the x value which gives a maximum for A, and I'm sure you know how to do this.