# Thread: Solving f(x) equation with a fraction

1. ## Solving f(x) equation with a fraction

I have this problem:

f(x) = 2X^2 + 6x - 1
find f(1/2)

The book says the answer is 5/2.

I can't seem to get this. I am missing something.

f(1/2) = 2(1/2)^2 + 6(1/2) - 1

2(1/4) + 6/2 - 1
2/4 + 6/2 - 1
This is where I am screwing up. I don't know the proper way to proceed.

EDIT I think I got it, does this look legit?

1/2 + 6/2 - 2/2

7/2 - 2/2

5/2

2. Originally Posted by mrnemo
I have this problem:

f(x) = 2X^2 + 6x - 1
find f(1/2)

The book says the answer is 5/2.

I can't seem to get this. I am missing something.

f(1/2) = 2(1/2)^2 + 6(1/2) - 1

2(1/4) + 6/2 - 1
2/4 + 6/2 - 1
This is where I am screwing up. I don't know the proper way to proceed.
I tried 1/4 + 2 and that doesn't work...

you just made mistake with $\frac {2}{4} = \frac {1}{2}$ .... it's not $\frac {1}{4}$

$\frac {2}{4} + \frac {6}{2} - 1 = \frac {1}{2} +3 - 1 = \frac {1}{2} +2 = \frac {1+4 }{2} = \frac {5}{2}$

Edit: yes you did correct now

3. Thanks. Yours is definitely cleaner. I appreciate the help.