Simplify the rational expression.

(45y-9xy)/(x^2y-25y)

I got an answer of 9y/y(x+5) but it seems to be wrong. Can anyone solve this for me and see what they get? Thank you

User Icon for MathMate MathMate answered
14 years ago

First take out obvious common factors

(45y-9xy)/(x^2y-25y)
=9y(5-9x)/y(x²-25)

cancel out the common factor y from the numerator and denominator and see if there are other factoring you can do.

User Icon for Alex Alex answered
14 years ago

I did that u get 9y(5-9x)/((x-5)(x+5)) but it is still wrong

User Icon for MathMate MathMate answered
14 years ago

Did you leave the "y" in the numerator?

User Icon for Alex Alex answered
14 years ago

sorry what I was suppose to write was 9y(5-9x)/y((x-5)(x+5))

do you see where there is still a mistake?

User Icon for MathMate MathMate answered
14 years ago

If you have a "y" both in the numerator and denominator, you can cancel them out as long as y≠0.

For example:
5y(x-1)/(25xy²)
=5y(x-1)/(5y(5xy)) ... here, remove 5y, a common factor
=(x-1)/(5xy)

User Icon for Alex Alex answered
14 years ago

so will the final answer be 9(5-9x)/((x-5)(x+5)) ?

User Icon for MathMate MathMate answered
14 years ago

Correct!

User Icon for Alex Alex answered
14 years ago

It still shows me as wrong when I submit online

User Icon for MathMate MathMate answered
14 years ago

Sorry, there was a mistake in:

(45y-9xy)/(x^2y-25y)
=9y(5-9x)/y(x²-25)

Should have read:
(45y-9xy)/(x^2y-25y)
=9y(5-x)/y(x²-25)

Now can you figure out the answer and try again?

User Icon for Explain Bot Explain Bot answered
11 months ago

To simplify the rational expression (45y-9xy)/(x^2y-25y), we can first factor out the common term '9y' from the numerator:

(45y-9xy)/(x^2y-25y) = 9y(5-x)/(y(x^2-25))

Next, the denominator can be factored as the difference of squares:

x^2-25 = (x+5)(x-5)

Applying this factorization to the expression:

9y(5-x)/(y(x^2-25)) = 9y(5-x)/(y(x+5)(x-5))

Now, we can cancel out the common factors:

9y cancels y:
= (5-x)/(x+5)(x-5)

Therefore, the simplified rational expression is (5-x)/(x+5)(x-5).