Give an example of a sum of two rational expressions with different denominators, then perform the operation by showing all the steps, including how you found the common denominator. These rational expressions must have a variable in the denominator, such as (3x+1) / (x^2 – 1). Give another example of a sum, ratio, product, or different of two rational expressions for your classmates to solve. Again, the example must have a variable in the denominator. When might you use rational expressions in real life?

Question

anonymous · Answer

3             x
---    +   ----
2x-1        x+1

lcd = (2x+1)(x+1)

now multiply each term by the lcd

= 3(x+1)   + x(2x-1)
   -----------------
       (2x+1)(x+1)

simplifying:

=      3x + 3 + 2x^2 - x
        ----------------
            (2x+1)(x+1)

=        2x^2 + 2x + 3
         -------------
             (2x+1)(x+1)