Question

Add:
(3/2a) + (5/2a)
Possible answers:
8/4a, 2/a, 15/4a2^ or 4/a

Answer 1

get a common denominator... 2a

now add the numerators

Put the numerators over the common denominator. Reduce the fraction.

I will be happy to check your work

Answer 2

PsyDAG told you the answer is 8/2a. I told you to simplify his answer.

What is 8 divided by 2?

Answer 3

Sandra, the placing of brackets is crucial here
The way you placed them makes them insignificant, it is the same thing as

3/2a + 5/2a

According to the rules of operations, this is the same as
(3/2)a + (5/2)a
= (8/2)a
= 4a

so you must have meant:
3/(2a) + 5/(2a) , the way both bob and Ms Sue read your question
= 8/(2a)
= 4/a

Can you see why those brackets were absolutely essential ?

e.g.
suppose a = 10
then your expression is

3/2*10 + 5/2*10 = 40

http://www.wolframalpha.com/input/?i=3%2F2*10+%2B+5%2F2*10

vs

3/(2*10) + 5/(2*10) = 2/5

http://www.wolframalpha.com/input/?i=3%2F%282*10%29+%2B+5%2F%282*10%29+

Answer 4

Thank you, now I can.