Math  /  Algebra

QuestionSolve for xx in the equation below. Round your answer to the nearest hundredth. Do not round any intermediate computations. 4x+9=154^{x+9}=15

Studdy Solution

STEP 1

1. The equation 4(x+9)=15 4^{(x + 9)} = 15 is exponential.
2. We will use logarithms to solve for x x .

STEP 2

1. Take the logarithm of both sides.
2. Use logarithmic properties to solve for x x .
3. Calculate the value of x x and round to the nearest hundredth.

STEP 3

Take the natural logarithm (or any logarithm, but we'll use natural logarithm here) of both sides of the equation to bring the exponent down:
ln(4(x+9))=ln(15) \ln(4^{(x + 9)}) = \ln(15)

STEP 4

Use the power rule of logarithms, which states that ln(ab)=bln(a)\ln(a^b) = b \cdot \ln(a), to move the exponent in front:
(x+9)ln(4)=ln(15) (x + 9) \cdot \ln(4) = \ln(15)

STEP 5

Solve for x+9 x + 9 by dividing both sides by ln(4)\ln(4):
x+9=ln(15)ln(4) x + 9 = \frac{\ln(15)}{\ln(4)}

STEP 6

Isolate x x by subtracting 9 from both sides:
x=ln(15)ln(4)9 x = \frac{\ln(15)}{\ln(4)} - 9

STEP 7

Calculate the value of x x using a calculator. First, compute ln(15)ln(4)\frac{\ln(15)}{\ln(4)}, then subtract 9. Round the final answer to the nearest hundredth:
xln(15)ln(4)90.9531598.05 x \approx \frac{\ln(15)}{\ln(4)} - 9 \approx 0.95315 - 9 \approx -8.05
The value of x x rounded to the nearest hundredth is:
8.05 \boxed{-8.05}

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