High School

What is the solution to the equation below? (Round your answer to two decimal places.)

3 + 7 * log_5 x = 25

A. x = 369.33
B. x = 625.00
C. x = 55.90
D. x = 157.31

Answer :

To solve the equation [tex]3 + 7 \cdot \log_5 x = 25[/tex], we will follow the steps below:


  1. Subtract 3 from both sides:

    Start by isolating the logarithmic part:
    [tex]7 \cdot \log_5 x = 25 - 3[/tex]
    [tex]7 \cdot \log_5 x = 22[/tex]


  2. Divide both sides by 7:

    Isolate the logarithm completely by dividing both sides by 7:
    [tex]\log_5 x = \frac{22}{7}[/tex]


  3. Convert the logarithmic equation to an exponential equation:

    Recall that [tex]\log_b a = c[/tex] means [tex]b^c = a[/tex]. Therefore, [tex]5^{\frac{22}{7}} = x[/tex].


  4. Calculate [tex]x[/tex]:

    Use a calculator to find [tex]x[/tex] by evaluating [tex]5^{\frac{22}{7}}[/tex]:
    [tex]x \approx 369.33[/tex]



Hence, the solution to the equation is [tex]x = 369.33[/tex].

Therefore, the correct multiple-choice option is A. x = 369.33.