I am assuming that the original problem looks like this
Factoring the denominator of the second term like so will help.
Note: The factoring that you showed is wrong.
t² - 4 does NOT equal (t+4)(t-2)
If you are ever wondering if you have factored it properly, check!
(t+4)(t-2) = t² + 4t - 2t - 8
................= t² + 2t - 8
The proper factoring of t² - 4 is (t+2)(t-2).
Check if you wish to prove it to yourself.
Code:
t - 8
__ _________
t-2 (t+2)(t-2)
Then the common denominator is clear to see. It is (t+2)(t-2)
So what you must do now is multiply the first term by (t+2)/(t+2)
Note: Keep in mind that you are technically multiplying by 1, so you aren't really changing the term.
Code:
t(t+2) - 8
________ ________
(t-2)(t+2) (t+2)(t-2)
Can you take it from here?