How would i go about this problem can some one give me a step by step please

does anyone have a good tutorial so i can learn problems like this one?

18/13-10/17+3/2=?

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- Sep 13th 2009, 07:03 PM #1

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- Sep 13th 2009, 07:10 PM #2
$\displaystyle \frac{18}{13}-\frac{10}{17}+\frac{3}{2}$

Find a common denominator, the easiest way to find one is to multiply all the denominators together.

$\displaystyle 13\times 17 \times 2 = 442$

Now

$\displaystyle

\frac{18\times17\times 2}{442}-\frac{10\times13\times 2}{442}+\frac{3\times17\times 13}{442}

$

Can you finish it from here?

- Sep 13th 2009, 07:17 PM #3

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- Sep 13th 2009, 07:27 PM #4

- Sep 13th 2009, 07:39 PM #5

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- Sep 13th 2009, 08:14 PM #6
Well lets take the first term as a case study.

$\displaystyle \frac{18}{13}$

As you understand we need to make the denominator 13 into 442. This is done by multiplying by 17 and 2. I.e 13 by 17 by 2 = 442.

So if we are changing the demoninator by multiplying by 17 and 2, then we must also do this to the numerator.

$\displaystyle \frac{18}{13} = \frac{18\times 17 \times 2}{13\times 17 \times 2 } = \frac{18\times 17 \times 2}{442 } $

Now you need to do this to the 2nd and 3rd term.

- Sep 13th 2009, 08:25 PM #7

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- Sep 13th 2009, 08:57 PM #8
We didn't multiply the denominator by 13 so we don't times the numerator by 13 either, maybe this working will illustrate it better.

We are doing exactly the same to each the numerator and demoninator.

$\displaystyle \frac{18}{13} = \frac{18}{13}\left(\frac{\times 17 \times 2}{\times 17 \times 2 }\right) = \frac{18\times 17 \times 2}{442 }

$

- Sep 13th 2009, 10:02 PM #9

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You multiplied all the denominators together to get the final denominator.

So what is left is to multiply the numerator correct?

What the question i am referring to is the numerator, I can't get a grasp on why your multiplying. Sorry if I'm asking so many questions' but i am using this to write a study guide for myself, since i am home schooling. That is why i asked if their are tutorials on problems such as the one i presented with a in depth write up.

- Sep 13th 2009, 10:10 PM #10

I think I agree with what your saying

$\displaystyle \frac{18}{13}-\frac{10}{17}+\frac{3}{2} = \frac{18}{13}\left(\frac{\times 17 \times 2}{\times 17 \times 2 }\right)-$ $\displaystyle \frac{10}{17}\left(\frac{\times 13 \times 2}{\times 13 \times 2 }\right)+$ $\displaystyle \frac{3}{2}\left(\frac{\times 17 \times 13}{\times 17 \times 13 }\right) = \frac{18\times17\times 2}{442}-\frac{10\times13\times 2}{442}+\frac{3\times17\times 13}{442}$

Does that help?

I don't know of any tutorials to help you with this problem but I bet there is one. I think you should google "Addition of fractions" and see what you get.

- Sep 13th 2009, 11:04 PM #11

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