1. **Problem statement:** Differentiate the following functions:
a) $g(x) = (x^2 - 2)(2x + 3)$
b) $f(x) = \frac{2x - 5}{x + 1}$
c) $y = (x^2 + 1)^7$
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2. **Formulas and rules:**
- Product rule: $\frac{d}{dx}[u(x)v(x)] = u'(x)v(x) + u(x)v'(x)$
- Quotient rule: $\frac{d}{dx}\left[\frac{u(x)}{v(x)}\right] = \frac{u'(x)v(x) - u(x)v'(x)}{(v(x))^2}$
- Chain rule: $\frac{d}{dx}[f(g(x))] = f'(g(x)) \cdot g'(x)$
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3. **Solution:**
**a) Differentiate $g(x) = (x^2 - 2)(2x + 3)$ using the product rule:**
Let $u = x^2 - 2$, $v = 2x + 3$
Calculate derivatives:
$u' = 2x$
$v' = 2$
Apply product rule:
$$g'(x) = u'v + uv' = (2x)(2x + 3) + (x^2 - 2)(2)$$
Expand terms:
$$= 4x^2 + 6x + 2x^2 - 4$$
Combine like terms:
$$= (4x^2 + 2x^2) + 6x - 4 = 6x^2 + 6x - 4$$
**b) Differentiate $f(x) = \frac{2x - 5}{x + 1}$ using the quotient rule:**
Let $u = 2x - 5$, $v = x + 1$
Calculate derivatives:
$u' = 2$
$v' = 1$
Apply quotient rule:
$$f'(x) = \frac{u'v - uv'}{v^2} = \frac{2(x + 1) - (2x - 5)(1)}{(x + 1)^2}$$
Simplify numerator:
$$= \frac{2x + 2 - 2x + 5}{(x + 1)^2} = \frac{7}{(x + 1)^2}$$
**c) Differentiate $y = (x^2 + 1)^7$ using the chain rule:**
Let outer function $f(u) = u^7$ and inner function $u = x^2 + 1$
Calculate derivatives:
$f'(u) = 7u^6$
$u' = 2x$
Apply chain rule:
$$\frac{dy}{dx} = f'(u) \cdot u' = 7(x^2 + 1)^6 \cdot 2x = 14x(x^2 + 1)^6$$
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**Final answers:**
$$g'(x) = 6x^2 + 6x - 4$$
$$f'(x) = \frac{7}{(x + 1)^2}$$
$$\frac{dy}{dx} = 14x(x^2 + 1)^6$$
Differentiate Functions E156E5
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