Differentiate Functions
1. Differentiate $f(x) = x^2 + \frac{1}{x^2}$.
- Rewrite $\frac{1}{x^2}$ as $x^{-2}$.
- Use power rule: $\frac{d}{dx}x^n = nx^{n-1}$.
- So, $f'(x) = 2x + (-2)x^{-3} = 2x - \frac{2}{x^3}$.
2. Differentiate $f(x) = (x^2 + x + 1)(x^2 + 2)$.
- Use product rule: $(uv)' = u'v + uv'$.
- Let $u = x^2 + x + 1$, $v = x^2 + 2$.
- Compute derivatives: $u' = 2x + 1$, $v' = 2x$.
- Thus, $f'(x) = (2x + 1)(x^2 + 2) + (x^2 + x + 1)(2x)$.
- Expand: $= (2x^3 + 4x + x^2 + 2) + (2x^3 + 2x^2 + 2x)$.
- Combine like terms: $4x^3 + 3x^2 + 6x + 2$.
3. Differentiate $f(x) = \frac{3x - 1}{2x + 1}$.
- Use quotient rule: $\frac{u'v - uv'}{v^2}$.
- Let $u = 3x - 1$, $v = 2x + 1$.
- Derivatives: $u' = 3$, $v' = 2$.
- So, $f'(x) = \frac{3(2x + 1) - (3x - 1)(2)}{(2x + 1)^2}$.
- Numerator: $6x + 3 - 6x + 2 = 5$.
- Hence, $f'(x) = \frac{5}{(2x + 1)^2}$.
4. Differentiate $f(x) = \frac{2x}{9 + x^2}$.
- Use quotient rule with $u = 2x$, $v = 9 + x^2$.
- Derivatives: $u' = 2$, $v' = 2x$.
- So, $f'(x) = \frac{2(9 + x^2) - 2x(2x)}{(9 + x^2)^2} = \frac{18 + 2x^2 - 4x^2}{(9 + x^2)^2} = \frac{18 - 2x^2}{(9 + x^2)^2}$.
5. Differentiate $f(x) = \frac{1 - x}{2 + x}$.
- Using quotient rule with $u = 1 - x$, $v = 2 + x$.
- Derivatives: $u' = -1$, $v' = 1$.
- So, $f'(x) = \frac{-1(2 + x) - (1 - x)(1)}{(2 + x)^2} = \frac{-2 - x - 1 + x}{(2 + x)^2} = \frac{-3}{(2 + x)^2}$.
6. Differentiate $f(x) = 6x^3 \cdot 7x^4$.
- First simplify: $f(x) = 42x^{3 + 4} = 42x^7$.
- Use power rule: $f'(x) = 42 \cdot 7 x^{6} = 294 x^{6}$.
7. Differentiate $f(x) = 3x^4 - 2x^3 + x^2 - 4x + 2$.
- Differentiate each term:
- $\frac{d}{dx}3x^4 = 12x^3$, $\frac{d}{dx}(-2x^3) = -6x^2$, $\frac{d}{dx}x^2 = 2x$, $\frac{d}{dx}(-4x) = -4$, derivative of constant 2 is 0.
- Combine: $f'(x) = 12x^3 - 6x^2 + 2x - 4$.
Final answers:
1. $2x - \frac{2}{x^3}$
2. $4x^3 + 3x^2 + 6x + 2$
3. $\frac{5}{(2x + 1)^2}$
4. $\frac{18 - 2x^2}{(9 + x^2)^2}$
5. $\frac{-3}{(2 + x)^2}$
6. $294 x^6$
7. $12x^3 - 6x^2 + 2x - 4$