5

Set 7: Exponential Functions (Advanced)

Explanation

Answer: A

Solve for xx: e3x=8e^{3x} = 8

A.

x=ln(8)3x = \frac{\ln(8)}{3}

✓ Correct
B.

x=3ln(8)x = 3\ln(8)

C.

x=83x = \frac{8}{3}

D.

x=ln(8)3x = \ln(8) - 3

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Use natural logarithm to solve. 1. Take natural log: ln(e3x)=ln(8)\ln(e^{3 x}) = \ln(8). 2. Simplify: 3x=ln(8)3x = \ln(8) (since ln(ea)=a\ln(e^a) = a). 3. Solve: x=ln(8)3x = \frac{\ln(8)}{3}. 4. Numerical: ln(8)2.079\ln(8) \approx 2.079, so x0.693x \approx 0.693. Strategic Tip: Natural log is the inverse of exe^x: ln(ex)=x\ln(e^x) = x. Choice B is incorrect because this multiplies by 3 instead of dividing. Choice C is incorrect because logarithms are needed, not simple division. Choice D is incorrect because subtraction is wrong.

Key Steps:

The correct answer is x=ln(8)3x = \frac{\ln(8)}{3}

Why others are wrong:
B: Choice B is incorrect and may result from a calculation error.
C: Choice C is incorrect and may result from a calculation error.
D: Choice D is incorrect and may result from a calculation error.

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