Solved on Feb 06, 2024

Find the derivative of f(x)=(x3+x2)tanxf(x) = (x^{3} + x^{2})^{\tan x} using logarithmic differentiation.

STEP 1

Assumptions
1. The function to differentiate is f(x)=(x3+x2)tanx f(x) = \left(x^{3} + x^{2}\right)^{\tan x} .
2. We will use logarithmic differentiation which involves taking the natural logarithm of both sides of the equation f(x) f(x) and then differentiating implicitly.
3. The rules of differentiation that will be used include the chain rule, product rule, and the derivative of natural logarithm.

STEP 2

Begin by taking the natural logarithm of both sides of the equation to simplify the differentiation process. Let y=f(x) y = f(x) , then take the logarithm of y y .
ln(y)=ln((x3+x2)tanx) \ln(y) = \ln\left(\left(x^{3} + x^{2}\right)^{\tan x}\right)

STEP 3

Apply the property of logarithms that allows us to bring the exponent in front as a multiplier.
ln(y)=tanxln(x3+x2) \ln(y) = \tan x \cdot \ln\left(x^{3} + x^{2}\right)

STEP 4

Now, differentiate both sides of the equation with respect to x x . Remember to use the product rule on the right-hand side, where the product rule states that (uv)=uv+uv (uv)' = u'v + uv' .
ddx[ln(y)]=ddx[tanxln(x3+x2)] \frac{d}{dx}[\ln(y)] = \frac{d}{dx}[\tan x \cdot \ln\left(x^{3} + x^{2}\right)]

STEP 5

Differentiate the left-hand side using the chain rule, where ddx[ln(y)]=1ydydx \frac{d}{dx}[\ln(y)] = \frac{1}{y} \cdot \frac{dy}{dx} .
1ydydx=ddx[tanxln(x3+x2)] \frac{1}{y} \cdot \frac{dy}{dx} = \frac{d}{dx}[\tan x \cdot \ln\left(x^{3} + x^{2}\right)]

STEP 6

Apply the product rule to the right-hand side.
1ydydx=ddx[tanx]ln(x3+x2)+tanxddx[ln(x3+x2)] \frac{1}{y} \cdot \frac{dy}{dx} = \frac{d}{dx}[\tan x] \cdot \ln\left(x^{3} + x^{2}\right) + \tan x \cdot \frac{d}{dx}[\ln\left(x^{3} + x^{2}\right)]

STEP 7

Differentiate tanx \tan x and ln(x3+x2) \ln\left(x^{3} + x^{2}\right) separately.
1ydydx=sec2xln(x3+x2)+tanx1x3+x2ddx(x3+x2) \frac{1}{y} \cdot \frac{dy}{dx} = \sec^{2}x \cdot \ln\left(x^{3} + x^{2}\right) + \tan x \cdot \frac{1}{x^{3} + x^{2}} \cdot \frac{d}{dx}\left(x^{3} + x^{2}\right)

STEP 8

Differentiate x3+x2 x^{3} + x^{2} using the power rule, where ddx[xn]=nxn1 \frac{d}{dx}[x^n] = nx^{n-1} .
1ydydx=sec2xln(x3+x2)+tanx1x3+x2(3x2+2x) \frac{1}{y} \cdot \frac{dy}{dx} = \sec^{2}x \cdot \ln\left(x^{3} + x^{2}\right) + \tan x \cdot \frac{1}{x^{3} + x^{2}} \cdot \left(3x^{2} + 2x\right)

STEP 9

Simplify the expression by combining like terms.
1ydydx=sec2xln(x3+x2)+tanx3x2+2xx3+x2 \frac{1}{y} \cdot \frac{dy}{dx} = \sec^{2}x \cdot \ln\left(x^{3} + x^{2}\right) + \tan x \cdot \frac{3x^{2} + 2x}{x^{3} + x^{2}}

STEP 10

Now, solve for dydx \frac{dy}{dx} by multiplying both sides by y y , which is f(x)=(x3+x2)tanx f(x) = \left(x^{3} + x^{2}\right)^{\tan x} .
dydx=y(sec2xln(x3+x2)+tanx3x2+2xx3+x2) \frac{dy}{dx} = y \cdot \left(\sec^{2}x \cdot \ln\left(x^{3} + x^{2}\right) + \tan x \cdot \frac{3x^{2} + 2x}{x^{3} + x^{2}}\right)

STEP 11

Substitute y y back with f(x) f(x) .
dydx=(x3+x2)tanx(sec2xln(x3+x2)+tanx3x2+2xx3+x2) \frac{dy}{dx} = \left(x^{3} + x^{2}\right)^{\tan x} \cdot \left(\sec^{2}x \cdot \ln\left(x^{3} + x^{2}\right) + \tan x \cdot \frac{3x^{2} + 2x}{x^{3} + x^{2}}\right)

STEP 12

This is the final expression for the derivative of f(x) f(x) .
f(x)=(x3+x2)tanx(sec2xln(x3+x2)+tanx3x2+2xx3+x2) f'(x) = \left(x^{3} + x^{2}\right)^{\tan x} \cdot \left(\sec^{2}x \cdot \ln\left(x^{3} + x^{2}\right) + \tan x \cdot \frac{3x^{2} + 2x}{x^{3} + x^{2}}\right)

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