Question

how do you find the least common denominator for a rational expression?

Answer 1

you factor out the denominators and see what each one is missing...

Answer 2

that's it? you think you could give me an example?

Answer 3

I could, but itd be easier if you had a problem we could work :)

Answer 4

suppose these are the bottoms of two glorified fractions(rational expressions)...

Answer 5

(x+2)(x+1) and (x+2)(x)

Answer 6

what do they need to "look alike"?

Answer 7

+1

Answer 8

good, but alittle of track. Think of the ()paranthesis as being a single number wrapped up. We cant just go adding a +1 to everything :)

the left one is missing an (x) the right one is missing a (x+1)

the common "numbers" are going to be:

(x)(x+1)(x+2) dos that make sense?

Answer 9

1 1
----- + ----- what would our common denominator of this be?
(x-3) (x)

Answer 10

(x-3)?

Answer 11

lets replace our "x" with a real value, lets use the number 5 and see if this turns this into somethng more familiar...

1 1
----- + -----
(5-3) (5)


1 1
----- + ----- what would our common denominator of this be?
2 5

Answer 12

10?

Answer 13

10 is correct..now how do we make each side have a denominator of 10?

Answer 14

multiply 2 by 5 and 5 by2?

Answer 15

thats is right.... now lets use that knowledge when we turn the 5 back into an "x".

1 1
----- + ----- what would our common denominator of this be?
(x-3) (x)

You do it the EXACT same way you did with the numbers, just think of the paranthesis as a single "wrapped up" number ok...

Answer 16

so i multiply-3 to (x)?

Answer 17

i hope to continue this later i have to get going thanks!!!!!

Answer 18

close..... your almost there :)

but tell me.. is one of our numbers a (-3)?

We have two "numbers": (x-3) and (x) those are the only two "numbers" we want to use.

There is no (-3) in our example...... only a number that is equal to (x-3) and another number that is equal to (x).

Answer 19

ok :) Ciao