Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta
    • Thread Starter
    Offline

    9
    ReputationRep:
    http://prntscr.com/b0751l
    Offline

    13
    ReputationRep:
    \frac{4}{x(x+3)}+\frac{5}{x+3} = \frac{4}{x(x+3)}+\frac{5x}{x(x+3  )} = \frac{4+5x}{x(x+3)}

    Common denominator is x(x+3)

    Your working out is not wrong but it isn't the best way. Don't expand the denominator!
    • Thread Starter
    Offline

    9
    ReputationRep:
    (Original post by Math12345)
    \frac{4}{x(x+3)}+\frac{5}{x+3} = \frac{4}{x(x+3)}+\frac{5x}{x(x+3  )} = \frac{4+5x}{x(x+3)}

    Common denominator is x(x+3)
    ugh im so confused
    • Thread Starter
    Offline

    9
    ReputationRep:
    (Original post by Math12345)
    \frac{4}{x(x+3)}+\frac{5}{x+3} = \frac{4}{x(x+3)}+\frac{5x}{x(x+3  )} = \frac{4+5x}{x(x+3)}

    Common denominator is x(x+3)

    Your working out is not wrong but it isn't the best way. Don't expand the denominator!
    Its just with other questions the video i watched said to do it that way ;/
    Offline

    13
    ReputationRep:
    (Original post by junayd1998)
    ugh im so confused
    For example:
    \frac{4}{18} + \frac{5}{6} = \frac{4}{18} + \frac{15}{18} = \frac{19}{18}
    Since the common denominator is 18.

    With your question the denominators are x(x+3) and (x+3) so the lowest common denominator is x(x+3).
    Offline

    13
    ReputationRep:
    (Original post by junayd1998)
    Its just with other questions the video i watched said to do it that way ;/
    The question helped you by giving the denominator factorised. You don't need to expand it.

    Steps:
    1. Find (lowest) common denominator.
    2. Cross multiply and expand at the numerator.
    3. Combine.

    For example:

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

    (where the lowest common denominator is (x+1)(x+2))
    Offline

    13
    ReputationRep:
    Try:

    \frac{4x}{(x+2)(x+1)} + \frac{5}{(x+2)}}
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: May 4, 2016
Poll
Do you like carrot cake?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.