Question

[(5/x)-(2/y )] ÷ [(-4/x)-(6/y)]
The answer key on the textbook is
(2x-5y)÷2(3x+2y)
But I got
(5y-2x)÷(-4y-6x)
Does anyone know how to do this?

Answer 1

Actually, the answers are exactly the same! In your answer, however, you will note that if you cancel a -1 from top and bottom, you will get the textbook answer.

Answer 2

I ment by "cancel a -1", cancel -1.

Answer 3

Does that help?

Answer 4

I don't really understand it.

Answer 5

How they are the same though?

Answer 6

If you factor out -1 from the numerator of your answer, you get -1(2x-5y), simple algebra. If you factor out -2 from the denominator, you get -2(2x+3y), also simple algebra.
Now divide top and bottom by -1 to get (2x-5y)/2(2x+3y). Looks familiar?

Answer 7

Yes! But how should I know when should I factor out -1?

Answer 8

Your answer is technically correct, even if you don't factor out the -1. The factoring just proves to you that the two answers are the same.

Answer 9

Oh! Now I get it!!

Answer 10

Good work. :)

Answer 11

Thank you!!!

Answer 12

No problem--I needed something to do