Product Rule 632C9A
1. **Problem:** Differentiate the function $$h(x) = (2x + 5)^7 (3x^4 - 8)^5$$.
2. **Formula and rules:** To differentiate a product of two functions, use the product rule:
$$\frac{d}{dx}[u(x)v(x)] = u'(x)v(x) + u(x)v'(x)$$
where $$u(x) = (2x + 5)^7$$ and $$v(x) = (3x^4 - 8)^5$$.
3. **Differentiate each part:**
- For $$u(x)$$, use the chain rule:
$$u'(x) = 7(2x + 5)^6 \cdot \frac{d}{dx}(2x + 5) = 7(2x + 5)^6 \cdot 2 = 14(2x + 5)^6$$.
- For $$v(x)$$, also use the chain rule:
$$v'(x) = 5(3x^4 - 8)^4 \cdot \frac{d}{dx}(3x^4 - 8) = 5(3x^4 - 8)^4 \cdot 12x^3 = 60x^3(3x^4 - 8)^4$$.
4. **Apply the product rule:**
$$h'(x) = u'(x)v(x) + u(x)v'(x) = 14(2x + 5)^6 (3x^4 - 8)^5 + (2x + 5)^7 60x^3 (3x^4 - 8)^4$$.
5. **Factor common terms:**
Both terms share $$ (2x + 5)^6 (3x^4 - 8)^4 $$, so factor it out:
$$h'(x) = (2x + 5)^6 (3x^4 - 8)^4 \left[14(3x^4 - 8) + 60x^3 (2x + 5) \right]$$.
6. **Simplify inside the bracket:**
$$14(3x^4 - 8) = 42x^4 - 112$$
$$60x^3 (2x + 5) = 120x^4 + 300x^3$$
Sum:
$$42x^4 - 112 + 120x^4 + 300x^3 = (42x^4 + 120x^4) + 300x^3 - 112 = 162x^4 + 300x^3 - 112$$.
7. **Final derivative:**
$$h'(x) = (2x + 5)^6 (3x^4 - 8)^4 (162x^4 + 300x^3 - 112)$$.
This is the derivative of the given function using the product and chain rules.