# Rational expressions

• Sep 15th 2006, 03:30 PM
danielle_54321
Rational expressions
Simplifying Rational expressions.

4x + 4/ 3x-3 X 6x - 6/5x+5

the question askes to simplify by bringing both terms to lowest common terms before multiplying. The answer is supposed to be 8/5, where 1, -1 are not equal to zero.

I can't figure out how to obtain my result. Here is my rough work, could someone help me to figure out what I am doing wrong?

4x + 4/ 3x-3 X 6x - 6/5x+5

= 4x + 4/ 1-1 X 2-2/5x+5

=4x + 4/ 0 X 0/5x+5

= 0/0 = undefined. (we are supposed to "cross-cancel" by crossing out like terms and such)
• Sep 15th 2006, 04:04 PM
OReilly
Quote:

Originally Posted by danielle_54321
Simplifying Rational expressions.

4x + 4/ 3x-3 X 6x - 6/5x+5

the question askes to simplify by bringing both terms to lowest common terms before multiplying. The answer is supposed to be 8/5, where 1, -1 are not equal to zero.

I can't figure out how to obtain my result. Here is my rough work, could someone help me to figure out what I am doing wrong?

4x + 4/ 3x-3 X 6x - 6/5x+5

= 4x + 4/ 1-1 X 2-2/5x+5

=4x + 4/ 0 X 0/5x+5

= 0/0 = undefined. (we are supposed to "cross-cancel" by crossing out like terms and such)

Frenkly I can't figure what is what in 4x + 4/ 3x-3 X 6x - 6/5x+5
Please use parentheses so we could clearly see what is what.

And also using x and X... please clarify expression.
• Sep 15th 2006, 04:12 PM
OReilly
Quote:

Originally Posted by OReilly
Frenkly I can't figure what is what in 4x + 4/ 3x-3 X 6x - 6/5x+5
Please use parentheses so we could clearly see what is what.

And also using x and X... please clarify expression.

Well, I have figured out what expression you need to simplify.

The expression is (if I am right):

[(4x+4)/(3x-3)] *[(6x-6)/(5x+5)]

So if I am right then solution is:

[(4x+4)/(3x-3)] *[(6x-6)/(5x+5)] =
[(4(x+1))/(3(x-1))] *[(6(x-1))/(5(x+1))] =
(4/3) * (6/5) = 24/15 = 8/5

x must be different then 1 and -1.