Question 71283
You wrote " b/b-1 + 2b/b^2-1 simplify" but sorry to say this is a lousy way to write an expression as it has changed the meaning . Instead should have been 
written as :-   " b/(b-1) + 2b/(b^2-1) simplify".

Now,
  b/(b-1) + 2b/(b^2-1)
= b(b+1)/((b-1)(b+1)) + 2b/(b^2-1)                 as  (b-1)(b+1)=b^2-1  so you can say that i have made the denominators of the two terms equal.

= b(b+1)/((b-1)(b+1)) + 2b/((b-1)(b+1))
= (b^2 + b + 2b)/((b-1)(b+1))
= (b^2 + 3b)/((b-1)(b+1))
= b(b+3)/((b-1)(b+1))  Answer.
cheers!