
rate question
Question asks to find the rate of atmospheric pressure changing for a rocket rising vertically at 5km/s when at an altitude of 1km.
Given the relationship of atmospheric pressure (in milibars) at an altitude of x kilometres is given by 1000(0.88)^x.
I just can't see how to differentiate the function. Anyone?

integrate?
the question is asking for a rate of change ... sounds like a derivative to me.

Sorry yes I meant differentiate, I cannot see how to differentiate it.

$\displaystyle \frac{d}{dt} a^x = a^x \cdot \ln{a} \cdot \frac{dx}{dt}$

Is this right?
$\displaystyle
\begin{array}{l}
\frac{d}{{dt}}P(x) = \frac{d}{{dt}}[1000(0.88)^x ] \\
= 0.88^x \ln (0.88)\frac{{dx}}{{dt}} \\
\end{array}
$

Is this right?
$\displaystyle
\begin{array}{l}
\frac{d}{{dt}}P(x) = \frac{d}{{dt}}[1000(0.88)^x ] \\
= 0.88^x \ln (0.88)\frac{{dx}}{{dt}} \\
\end{array}
$

what happened to the constant 1000?