# 51 year-old dad who has no clue...

#### fhtorres

##### New member
I have been going over the examples in my daughter's book and none of them help me get started.

a/(ab-b^2)+b/(ab-a^2)

#### Jomo

##### Elite Member
You really did not ask a question. I assume that you want to add these two fractions?

Then you need to get a common denominator.
I will factor the left denominator and you/your daughter can try to factor the 2nd denominator and come up with a common denominator--preferable the least common denominator

(ab-b^2) = b(a-b)

#### Otis

##### Senior Member
Hello fhtorres. As outlined in the forum's guidelines, we need the instructions that came with the exercise. Thanks!

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#### pka

##### Elite Member
I have been going over the examples in my daughter's book and none of them help me get started.a/(ab-b^2)+b/(ab-a^2)
$$\displaystyle \dfrac{a}{ab-b^2}+\dfrac{b}{ab-a^2}=\\\dfrac{a}{b((a-b)}+\dfrac{b}{a(b-a)}=\\\dfrac{a}{b((a-b)}-\dfrac{b}{a(a-b)}=\\\dfrac{1}{(a-b)}\left(\dfrac{a}{b}-\dfrac{b}{a}\right)$$
Can you finish?