1. The problem is to differentiate a function using the chain rule. 2. The chain rule formula is: $$\frac{dy}{dx} = \frac{dy}{du} \cdot \frac{du}{dx}$$ where $y$ is a function of $u$, and $u$ is a function of $x$. 3. Important rule: When you have a composite function like $y = f(g(x))$, you first differentiate the outer function $f$ with respect to the inner function $g(x)$, then multiply by the derivative of the inner function $g(x)$ with respect to $x$. 4. For example, if $y = (3x+2)^5$, let $u = 3x+2$, so $y = u^5$. 5. Differentiate $y$ with respect to $u$: $$\frac{dy}{du} = 5u^4$$ 6. Differentiate $u$ with respect to $x$: $$\frac{du}{dx} = 3$$ 7. Apply the chain rule: $$\frac{dy}{dx} = 5u^4 \cdot 3 = 15(3x+2)^4$$ 8. So the derivative of $y = (3x+2)^5$ is $$\frac{dy}{dx} = 15(3x+2)^4$$. This is how you use the chain rule to differentiate composite functions.