A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

Someone help to explain this please!! log x + log (x + 48) = 2

  • This Question is Closed
  1. campbell_st
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    well using log laws for multiplication the problem can be written as \[\log(x(x + 48)) = 2~~~or~~~~\log(x^2 + 48x) = 2\] if this is a base 10 log system them raise each side of the equation to a power of 10 and you need to know the log law \[a^{\log_{a}(b)} = b\] so \[10^{\log(x^2 + 48x)} = 10^2\] which becomes \[x^2 + 48x = 100\] now you can solve for x and remember you can't take the log of a negative number when you consider the solutions.

  2. Hero
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @calecea Any questions about Campbell_st approach here?

  3. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @Hero no, I think I got it.

  4. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @campbell_st , so does x=4.9? I did square root to both sides, then added the x and got 49, then divided by 10.

  5. campbell_st
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    well I would rewrite it as \[x^2 + 48x - 100 = 0\] and this factors to (x - 2)(x + 50) = 0 so the solutions seem to be x = 2 and x = -50

  6. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh, I didn't know it was supposed to be written that way.

  7. campbell_st
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    well lets look at the positive value x = 2 you get log(2) + log(2 + 48) this can be rewritten as log(2 x 50) = log(100) and 100 = 10^2 so it seems to make sense

  8. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh ok, Thank you!

  9. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.