# Rational Expressions

• Mar 19th 2007, 03:45 PM
Natalie
Rational Expressions
What would be the common denominator for these three demoninators
2x, 4, 2x+3

thanks so much....would it just be to multiply all three by each other?
• Mar 19th 2007, 03:50 PM
Jhevon
Quote:

Originally Posted by Natalie
What would be the common denominator for these three demoninators
2x, 4, 2x+3

thanks so much....would it just be to multiply all three by each other?

multiplying each other would be one way to do it, but it's a slight overkill.

4x(2x + 3) would do it, as oppsed to the 8x(2x + 3) you would get if you multiply all three. it's no big deal though, if you use 8x(2x + 3) the extra 2 would eventually cancal out, and maybe more
• Mar 19th 2007, 03:58 PM
Natalie
oooh great thanks so much, that helps.

so is there any faster ways in simplifying this?

4x
---------
(x+5)(x-1)

subract

5
---
4

thanks again
• Mar 19th 2007, 04:09 PM
Jhevon
Quote:

Originally Posted by Natalie
oooh great thanks so much, that helps.

so is there any faster ways in simplifying this?

4x
---------
(x+5)(x-1)

subract

5
---
4

thanks again

..........4x .........................5
...------------.....-..........-----
....(x+5)(x-1).....................4

...........8x...-...5(x + 5)(x - 1)
..= ..-------------------------
.............4(x + 5)(x - 1)

...........8x...-...5(x^2 + 4x - 5)
..= ..---------------------------
.............4(x + 5)(x - 1)

...........8x...-...(5x^2 + 20x - 25)
..= ..---------------------------
...............4(x + 5)(x - 1)

............-5x^2 -12x + 25
..= ..---------------------------
...............4(x + 5)(x - 1)