Question
Suppose that $f(x)$ and $g(x)$ are differentiable and negative everywhere. If $f^{\prime}(x)>0$ and $g^{\prime}(x)>0$ everywhere, show that $h(x)=f(x) g(x)$ is a decreasing function.
Step 1
Since $f(x)$ and $g(x)$ are negative everywhere, we know that $f(x) < 0$ and $g(x) < 0$ for all $x$. Show more…
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