Results 1 to 4 of 4

Math Help - last minute math problems plz help!

  1. #1
    Newbie
    Joined
    Jan 2009
    Posts
    6

    last minute math problems plz help!

    how would i go on about solving this? give me some steps to understand plz
    Follow Math Help Forum on Facebook and Google+

  2. #2
    No one in Particular VonNemo19's Avatar
    Joined
    Apr 2009
    From
    Detroit, MI
    Posts
    1,823
    There's nothing to 'solve' here, but we can simplify like so:

    \frac{x^2-1}{5x^2+5x}*\frac{15x^2}{3x-3}

    =\frac{(x-1)(x+1)}{5x(x+1)}*\frac{3(5x^2)}{3(x-1)}

    Looks like we can do some cancelling here......

    =\frac{(x-1)}{5x}*\frac{5x^2}{(x-1)}

    and more cancelling.........

    \frac{1}{1}*\frac{x}{1}=x

    How 'bout that?

    The other problems similar. You can do it. I know you can.

    fOR THE DIVISION PROBLEMS,JUST FLIP THE FRACTION ON THE RIGHT AND MULTIPLY. JUST BECAUSE YOU'RE DEALING WITH MORE COMLICATED NUMERATORS AND DENOMINATORS, THEY'RE STILL JUST FRACTIONS.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    -1
    e^(i*pi)'s Avatar
    Joined
    Feb 2009
    From
    West Midlands, England
    Posts
    3,053
    Thanks
    1
    Quote Originally Posted by unify34 View Post
    how would i go on about solving this? give me some steps to understand plz
    Factorise whatever you can and try to cancel out common factors. Remember that \frac{a}{b} \cdot \frac{c}{d} = \frac{ac}{bd} and  \frac{a}{b} \div \frac{c}{d} = \frac{ad}{bc}

    I'll go through the first one:

    \frac{x^2-1}{5x^2+5x} \cdot \frac{15x^2}{3x-3}

    x^2-1 is the difference of two squares: (x^2-1) = (x-1)(x+1)
    5x^2+5x has a common factor of 5x: 5x(x+1)

    Now we see that an (x+1) can cancel to give the LHS:

    \frac{x-1}{5x}

    15x^2 doesn't need factorising, it will cancel in due course
    3x-3 has a common factor of 3: 3x-3 = 3(x-1)

    On the RHS we can cancel a 3: \frac{5x^2}{x-1}

    bring the two sides together:

    \frac{x-1}{5x} \times \frac{5x^2}{x-1}

    5x will cancel and so will x-1 which leaves a final answer of x
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie Singaporean's Avatar
    Joined
    May 2009
    From
    Singapore
    Posts
    19
    Just try to spot common terms so that you can cancel them away, simplifying the term. If not, you can make the denominator the same to combine the terms together.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. I need some help on some math problems
    Posted in the Math Puzzles Forum
    Replies: 5
    Last Post: February 27th 2010, 11:15 PM
  2. How far in first minute?
    Posted in the Differential Equations Forum
    Replies: 1
    Last Post: July 16th 2009, 02:59 PM
  3. math problems
    Posted in the Geometry Forum
    Replies: 0
    Last Post: January 3rd 2009, 07:58 AM
  4. 30 minute set theory
    Posted in the Math Topics Forum
    Replies: 3
    Last Post: September 24th 2008, 11:42 AM
  5. revolutions per minute??
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: September 19th 2007, 08:45 PM

Search Tags


/mathhelpforum @mathhelpforum