At what rate is this function increasing?

1. Apr 13, 2010

IntegrateMe

When x = 16,the rate at which $$\sqrt x$$ is increasing is $$\frac {1}{k}$$ times the rate at which x is increasing. What is the value of k?

2. Apr 13, 2010

IntegrateMe

I thought it would be 4 but the answer is 8.

3. Apr 13, 2010

jrosen13

Its the ratio of the derivatives evaluated at x=16,

(2 sqrt(x))^-1