Math  /  Calculus

QuestionDifferentiate the following function. y=(lnx)8+ln(x8)dydx=\begin{array}{l} y=(\ln x)^{8}+\ln \left(x^{8}\right) \\ \frac{d y}{d x}=\square \end{array} \square

Studdy Solution

STEP 1

What is this asking? We need to find the derivative of a function that has two parts: one is the natural logarithm of xx raised to the power of 8, and the other is the natural logarithm of xx raised to the power of 8. Watch out! Don't mix up the power rule and the chain rule!
Also, remember the properties of logarithms!

STEP 2

1. Rewrite the function
2. Differentiate the first term
3. Differentiate the second term
4. Combine the results

STEP 3

Let's **rewrite** our function yy to make it easier to differentiate.
We can use the **power rule of logarithms**: ln(ab)=bln(a)\ln(a^b) = b \cdot \ln(a).
So, ln(x8)\ln(x^8) becomes 8ln(x)8 \cdot \ln(x).

STEP 4

Our **rewritten function** now looks like this: y=(ln(x))8+8ln(x)y = (\ln(x))^8 + 8 \cdot \ln(x) Much cleaner!

STEP 5

Now, let's **differentiate** (ln(x))8(\ln(x))^8.
We'll need the **chain rule** here.
Think of it like this: we have an **inner function**, ln(x)\ln(x), and an **outer function**, something raised to the power of 8.

STEP 6

The chain rule says: **derivative of the outer function (with the inner function left alone) times the derivative of the inner function**.

STEP 7

The **derivative of the outer function** is 8(ln(x))78(\ln(x))^7.
The **derivative of the inner function**, ln(x)\ln(x), is 1x\frac{1}{x}.

STEP 8

Multiplying these together gives us: 8(ln(x))71x=8(ln(x))7x8(\ln(x))^7 \cdot \frac{1}{x} = \frac{8(\ln(x))^7}{x}

STEP 9

Next, let's **differentiate** 8ln(x)8 \cdot \ln(x).
Since 8 is a **constant**, we can just multiply it by the **derivative of** ln(x)\ln(x), which is 1x\frac{1}{x}.

STEP 10

This gives us: 81x=8x8 \cdot \frac{1}{x} = \frac{8}{x}

STEP 11

Finally, we **add the derivatives** of both terms to find the **derivative of the whole function**: dydx=8(ln(x))7x+8x\frac{dy}{dx} = \frac{8(\ln(x))^7}{x} + \frac{8}{x} We can also write this as: dydx=8(ln(x))7+8x\frac{dy}{dx} = \frac{8(\ln(x))^7 + 8}{x}

STEP 12

dydx=8(ln(x))7+8x\frac{dy}{dx} = \frac{8(\ln(x))^7 + 8}{x}

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