This is probably a piece of cake for most of you, but I haven't dealt with math in years so I could use a little help.
(1/a + 1/b) (1/a - 1/b)
So this is the starting point and it needs to be simplified. I have this from a friend and he said the solution is (1+a)/b . I'm not sure if that's correct, that's what I'm trying to find out.
This is how far I got:
(b^2 - a^2) / (a^2 * b^2)
And then (1 - a^2 / b^2) / a^2
From there I just go in circles... I'd appreciate if someone could tell me how to get to that solution (if it's correct...).
The expression is also equal to by difference of two squares (so your answer is correct).
I don't think your friend's answer is correct. For example, you could let a = b = 2, in which the correct answer is 0, but (1+a)/b = 3/2.