Posted by **Matt** on Monday, January 28, 2008 at 3:55pm.

SImplify:

(x - 9/x) / (1 + x/3)

and (m^-1 + n^-1) / (m^-3 + n^-3)

I have no idea what to do

- Algebra -
**Miley**, Monday, January 28, 2008 at 4:26pm
Answer to #2:

m^4n^2.

I subtracted the m's and subtracted the m's. It's one of the exponent rules.

I have NO idea how to do the first question.

- Algebra -
**Matt**, Monday, January 28, 2008 at 4:32pm
you cant do that, Miley, the m's and n's are separated by an addition sign, so you cant use the quotient of powers rule

- Algebra -
**Reiny**, Monday, January 28, 2008 at 9:23pm
for the first one, just multiply them using FOIL

to get

x + (x^2)/3 - 9/x - 3

for the second, use the rule for negative exponents to write

(1/m + 1/n)/(1/m^3 + 1/n^3)

finding common denominators and simplifying both top and bottom I got

(m+n)/mn / (m^3 + n^3)/m^3n^3

= (m+n)/mn * (m^3n^3)/(m^3 + n^3)

= m^2n^2(m+n) / (m^3 + n^3)

the bottom factors to (m+n)(m^2 - mn + n^2)

so we have

m^2n^2(m+n) / ((m+n)(m^2 - mn + n^2))

= m^2n^2 / (m^2 - mn + n^2)

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