Math  /  Algebra

QuestionSolve the following exponential equation. Express your answer as both an exact expression and a decimal approximation rounded to two decimal places. Use e=2.71828182845905e=2.71828182845905.

Studdy Solution

STEP 1

What is this asking? We need to find the value of xx that makes ee to a power equal to 5 to a power. Watch out! Remember the properties of logarithms and exponents!
Don't mix up the bases when applying logarithmic properties.

STEP 2

1. Take Natural Logarithms
2. Apply Logarithmic Properties
3. Isolate xx
4. Calculate the Result

STEP 3

Let's **take the natural logarithm** of both sides of our equation e3x+13=53x7e^{3x+13} = 5^{\frac{3x}{7}}.
Remember, we can do this because applying the same function to both sides of an equation maintains the equality.
We choose the natural log because it simplifies things when we have a base of ee. ln(e3x+13)=ln(53x7) \ln(e^{3x+13}) = \ln(5^{\frac{3x}{7}})

STEP 4

Now, let's use the **power rule of logarithms**: ln(ab)=bln(a)\ln(a^b) = b \cdot \ln(a).
This rule lets us bring those exponents down in front. (3x+13)ln(e)=3x7ln(5) (3x+13) \cdot \ln(e) = \frac{3x}{7} \cdot \ln(5)

STEP 5

Remember, ln(e)\ln(e) is just 1!
So, we can simplify our equation: 3x+13=3x7ln(5) 3x+13 = \frac{3x}{7} \cdot \ln(5)

STEP 6

Let's **move all the terms with** xx **to one side** of the equation and the **constant terms to the other**.
We'll subtract 3x3x from both sides: 13=3x7ln(5)3x 13 = \frac{3x}{7} \cdot \ln(5) - 3x

STEP 7

Now, we can **factor out** xx from the right side: 13=x(37ln(5)3) 13 = x \cdot \left( \frac{3}{7} \cdot \ln(5) - 3 \right)

STEP 8

To **completely isolate** xx, we'll **divide** both sides by (37ln(5)3)\left( \frac{3}{7} \cdot \ln(5) - 3 \right): x=1337ln(5)3 x = \frac{13}{\frac{3}{7} \cdot \ln(5) - 3}

STEP 9

Time to **plug in the value** for ln(5)\ln(5) which is approximately 1.60941.6094. x=13371.60943 x = \frac{13}{\frac{3}{7} \cdot 1.6094 - 3}

STEP 10

Let's **simplify the denominator**: x=130.68973 x = \frac{13}{0.6897 - 3} x=132.3103 x = \frac{13}{-2.3103}

STEP 11

Finally, we **calculate the value of** xx: x5.63 x \approx -5.63

STEP 12

The **exact solution** is x=1337ln(5)3x = \frac{13}{\frac{3}{7}\ln(5) - 3}.
The **approximate solution**, rounded to two decimal places, is x5.63x \approx -5.63.

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