# algebraic fraction question

• Mar 8th 2012, 01:52 AM
davellew69
algebraic fraction question
hi

can anyone clear my mind

Q. 1/3x -2/x+3

I understand tha I have to make both denominators the same and to do this I multiply them together.

I make the answer to be 3x^2+3 and would use this as the denominator, but the answer in my book tells me that the denomonator should be 3(x+3)
am I missing something?

Dave
• Mar 8th 2012, 01:59 AM
princeps
Re: algebraic fraction question
$\displaystyle \frac{1}{3} \cdot x -\frac{2}{x+3}=\frac {x(x+3)-6}{3(x+3)}$
• Mar 8th 2012, 02:12 AM
davellew69
Re: algebraic fraction question
why do I write 3(x+3)
• Mar 8th 2012, 02:26 AM
princeps
Re: algebraic fraction question
Quote:

Originally Posted by davellew69
why do I write 3(x+3)

$\displaystyle \frac{a}{b}+\frac{c}{d}=\frac{a \cdot d+b \cdot c}{b \cdot d}$
• Mar 8th 2012, 05:43 AM
Wilmer
Re: algebraic fraction question
Quote:

Originally Posted by davellew69
1/3x -2/x+3

Brackets required: x/3 - 2(x+3)