Results 1 to 3 of 3

Math Help - Help With A simple maths problem

  1. #1
    Newbie
    Joined
    Oct 2010
    Posts
    2

    Help With A simple maths problem

    Hi,

    First off the bat I need to say that I'm so bad at maths I'm not even sure what category this math problem belongs in so apologies if I've posted it in the wrong area.

    The Problem:

    I have this formula that I use to calculate a decibel level.

    db_gain=(x * (8 / 5)) - 90;

    When Using this formula db_gain value is not known and x value is known.

    How can I switch around? I.E db_gain is known but x is not?

    Thanks,

    dub
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Dec 2009
    Posts
    3,120
    Thanks
    1
    Quote Originally Posted by dubbeat View Post
    Hi,

    First off the bat I need to say that I'm so bad at maths I'm not even sure what category this math problem belongs in so apologies if I've posted it in the wrong area.

    The Problem:

    I have this formula that I use to calculate a decibel level.

    db_gain=(x * (8 / 5)) - 90;

    When Using this formula db_gain value is not known and x value is known.

    How can I switch around? I.E db_gain is known but x is not?

    Thanks,

    dub
    The formula has db_gain "in terms of x" so that you can calculate db_gain if x is known.

    You want x "in terms of db_gain" so that you can calculate x from db_gain.

    This requires moving the constants across to db_gain,
    either using rules or knowing why..

    \displaystyle\ db_-gain=x\ \frac{8}{5}-90

    \displaystyle\ db_-gain+90=x\ \frac{8}{5}+90-90=x\ \frac{8}{5}

    \displaystyle\ (db_-gain+90)\ \frac{5}{8}=x\ \frac{8}{5}\ \frac{5}{8}=x
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Oct 2010
    Posts
    2
    thanks for that. Showing the steps involved is especially useful
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Simple grade 9 maths question.
    Posted in the Algebra Forum
    Replies: 4
    Last Post: October 18th 2010, 02:47 PM
  2. Replies: 4
    Last Post: May 4th 2010, 09:08 AM
  3. Simple( discrete maths)
    Posted in the Discrete Math Forum
    Replies: 4
    Last Post: May 19th 2009, 12:43 PM
  4. Simple (ish) discrete maths help
    Posted in the Discrete Math Forum
    Replies: 5
    Last Post: May 19th 2009, 12:12 PM
  5. Replies: 0
    Last Post: September 5th 2007, 02:50 AM

Search Tags


/mathhelpforum @mathhelpforum