Explain how to solve [tex]$5^{x-2}=8$[/tex] using the change of base formula [tex]\log _b y=\frac{\log y}{\log b}[/tex]. Include the solution for [tex]x[/tex] in your answer. Round your answer to the thousandth.



Answer :

To solve the equation [tex]\(5^{x-2} = 8\)[/tex] using logarithms, follow these steps:

1. Take the logarithm of both sides:
We apply the common logarithm (logarithm base 10) to both sides of the equation:

[tex]\[ \log(5^{x-2}) = \log(8) \][/tex]

2. Use the power rule of logarithms:
The power rule states [tex]\(\log(a^b) = b \log(a)\)[/tex]. Using this rule, we can rewrite the left side:

[tex]\[ (x-2) \log(5) = \log(8) \][/tex]

3. Solve for [tex]\(x-2\)[/tex]:
Isolate [tex]\(x-2\)[/tex] by dividing both sides of the equation by [tex]\(\log(5)\)[/tex]:

[tex]\[ x-2 = \frac{\log(8)}{\log(5)} \][/tex]

4. Compute the values of [tex]\(\log(5)\)[/tex] and [tex]\(\log(8)\)[/tex]:
Using a calculator, we find:

[tex]\[ \log(5) \approx 0.698970 \][/tex]
[tex]\[ \log(8) \approx 0.903090 \][/tex]

5. Substitute these values back into the equation:
Plugging in the values, we get:

[tex]\[ x-2 = \frac{0.903090}{0.698970} \approx 1.292030 \][/tex]

6. Solve for [tex]\(x\)[/tex]:
Finally, add 2 to both sides to isolate [tex]\(x\)[/tex]:

[tex]\[ x = 1.292030 + 2 = 3.292030 \][/tex]

7. Round the answer to the nearest thousandth:
The final value of [tex]\(x\)[/tex] rounded to the nearest thousandth is:

[tex]\[ x \approx 3.292 \][/tex]

Thus, the solution to the equation [tex]\(5^{x-2} = 8\)[/tex], rounded to the nearest thousandth, is [tex]\(x \approx 3.292\)[/tex].