Math
posted by Monique .
For all real numbers, f(x)=(x^2+1)/2. If f(a)=25 and f(11)=b, what could be the value of ba?
I'm confused on how you do these problems. Can someone show me how to do them? Thanks much!

I will start you on b
f(11)=(11^2+1)/2=61 so b is 61
25=(a^2+1)/2 solve for a.... 
Ok, so f(25)=(25^2+1)/2. 626/2=313. So, a=313. When substituted, 61313 is 252.
There's a small issue though. This question is multiple, and I don't see a 252 as one of the choices:
a. 14
b. 36
c. 68
d. 77
e. 86
Did I do something wrong?