Question

explain why it is necessary to have common denominators when adding or subtracting rational expressions.

Answer 1

Spammers will be reported.

Answer 2

lol..another one!!!

Answer 3

Because if you don't, you can't add or subtract.

Answer 4

what does the word "denominator" mean?

Answer 5

medal for M.H

Answer 6

The number below the line in a common fraction; a divisor.

Answer 7

MEDALS FOR EVERYBODY!!!!

Answer 8

the denominator of a rational is basically the part that's below the line

Answer 9

it means "what you have" essentially. so if i have rials i can add them to rials, and if i have euros i can add them to euros, and and if i have dollars i can add them to dollars. but if i want to add euros to rials i have to convert one to the other, or else the addition makes no sense. like adding a cup of popcorn to a cup of mild

Answer 10

*milk

Answer 11

o_O

Answer 12

I HATE MILK!!

Answer 13

Good Answer +1

Answer 14

rational expressions are from mars; . . .

Answer 15

why is badman spamming :-(

Answer 16

I never ever get help on this site.

Answer 17

I think Satellite gave a good answer

Answer 18

think about adding 1/3 to 1/5

Answer 19

poor seafood!!

Answer 20

adding 1/3 of a pie of pizza + 1/5 of a pie of pizza

Answer 21

i can't write that there. LOL

Answer 22

its easier if you have a common unit or common division

Answer 23

GOODNIGHT PEOPLE!!!

Answer 24

what i can think of is, if we divide something equally, then only we can add them correctly.

Answer 25

i am happy to give a different answer, but i am not sure what kind of answer you are looking for
you cannot add
\[\frac{2}{x}+\frac{4}{x+5}\] without making the denominators the same. you cannot add unlike terms.

Answer 26

why i can't add them? that's the question

Answer 27

you you must have same denominators?

Answer 28

we can prove it algebraically.
given a/b + c/d = a*b^-1 + c*d^-1

Answer 29

you can add them. just like i can add
\[\frac{1}{2}+\frac{1}{3}\] or $20 + 50 cents

Answer 30

BYEEEE

Answer 31

now multiply by bd * (bd)^-1

Answer 32

but i have to make them the same first, i.e. i have to turn them into common units.

Answer 33

which is equal to 1

Answer 34

"common units" we can use that.

Answer 35

suppose i want to add 3 feet to 4 meters. i can do it, but i have to convert one to the other first

Answer 36

a/b + c/d = a*b^-1 + c*d^-1= [(bd)^-1*bd] ( a*b^-1 + c*d^-1)

Answer 37

and you can assume WLOG that that gcd (b,d) = 1

Answer 38

can i can write: it is important to make the denominators same b/c we have to add them proportionally