# Thread: Rate of change of Area in a Rectangle

1. ## Rate of change of Area in a Rectangle

Thank you =)

2. Hello,

Let $\displaystyle A$ be the area of the rectangle.

$\displaystyle A(t)=ab=(1+t^{1/3})^3 (10-\sqrt{t})^2$

What you look for is $\displaystyle \frac{dA}{dt}(64)$

So find the derivative for $\displaystyle A(t)$ and find its value at t=64.

3. Originally Posted by Moo
Hello,

Let $\displaystyle A$ be the area of the rectangle.

$\displaystyle A(t)=ab=(1+t^{1/3})^3 (10-\sqrt{t})^2$

What you look for is $\displaystyle \frac{dA}{dt}(64)$

So find the derivative for $\displaystyle A(t)$ and find its value at t=64.
Another consequence of not quoting the post you are replying to is this, the blighter has deleted his/her question leaving your answer hanging. This makes it more difficult for someone else to learn from what you have done.

(Quoting also makes it more difficult for someone who is trying to cheat in maths competions or on their exams to elliminate the evidence)

RonL

4. I'll do it next time
But I've got something like 50% of accuracy when it comes to quote things