how do you subtract fractions with unlike denominators?

Answer 1

multiply tops and bottoms so that the denominators are the same

a/b - c/d = (ad - bc) / (bd)

Answer 2

U have to find the LCM of the denominators and that will be the common denominator for the fractions.
For the problem 7/3 + 9/2
LCM of 3&2 is 6
Now 7/3 and 9/2 can be written as - 14/6 and 27/6 respectively.
Since they have the same denominator now you can add the numerators..
41/6 = 6 5/6
Hope that was some help. All the Best.

Answer 3

you have to get a common denominator...for example...

11/15 - 2/5 = 5/15....or 1/3

multiplying the denominator "5" by 3 will give you the common denominator of "15"...but you also have to multiply the numerator by the same number...after that you can work the equation...

11/15 - 6/15 = 5/15 or 1/3

another example is...

15/16 - 1/3 = ?

in this case the common denominator would be "48" because it is the smallest number that both denominators will divide into evenly...so multiply "15/16" by 3...which will equal 45/48...then multiply "1/3" by 16...which will equal 16/48...now you can subtract the fractions...

45/48 - 16/48 = 29/48

Answer 4

You have to convert to the lowest common denominator first, Best way is to multiply both denominators. The product will be the denominator you need to convert both fractions to.
Example: 1/3 - 1/4
1.) Multiple both denominators:3 X 4 = 12
2.) Convert your fractions
a,) To convert 1/3 to 12ths - you need to multiply by 4
4 X 1/3 = 4/12
b.) Convert 1/4 to 12ths - you need to multiply by 3
3 X 1/4 - 3/12
4.) Now 1/3 - 1/4 becomes 4/12 - 3/12. The answer 1/12

This work even with more than two fractions. Aklways find a common denominator first

Answer 5

Hi,

First you find a common denominator by finding multiples for each of the denominators until you find one they have in common ( you can also multiply the 2 denominators together to find a "quick" common denominator). Then create equivalent fractions. For example, 6/8 - 2/4 , the common denominator will be 8 because both 4 and 8 go into 8.Then make equivalent fractions 2/4 = how many 8ths? 4*2 is 8, so you multiply your numerator by the same number you used for the denominator: 2*2 = 4... Now you have 6/8- 4/8 = 2/8 and reduce to 1/4. I hope that explanation isn't as confusing as it looks to me! It's hard to type it out! =)

Answer 6

Find the LCD of both denominators, and change the fraction to the LCD.

For example

3/9 - 1/5

Factors of 9= 1, 3, 9
Factors of 5 = 1, 5

Nothing in common, so LCD = 9*5 = 45

To get 3/9 to have 45 in denominator, multiply by 5/5
For 1/5, multipy by 9/9

3/9 = 15/45
1/5 = 9/45

So we have 15/45- 9/45 = (15-9)/45 = 6/45 = 2/15

Answer 7

Just like adding fractions you change it to the least common denominator.

Example= 2/8 - 3/16 the least common denominator is 16

4/16-3/16 your answer is 1/16

Answer 8

you must multiply both numerators an denominators by a number that makes them the same

EX::

1/2 - 4/5 LCM of denominators= 10
*5 *2
5/10-8/10= 3/10

yay

Answer 9

Let us take an example of 1/3 and 1/5. We need to take a common denominator.

1/3 - 1/5 = (5 - 3) / 15 = 2 / 15.

I hope you got the idea.

Answer 10

No, u can't the denominators have to be the same in order to subtract them. So, what u should do is multiply the top and bottom by a number that will give u the same denominator and and add or subtract them!!!!!!!!!!!!!!!!!!

Answer 11

Make the denominators alike by multiplying by 1.

So 1/3 - 2/7 You could multiply the first one by 7/7 to get 7/21 and multiply the second one by 3/3 to get 6/21
So you get 7/21-6/21 = 1/21