math
posted by
Yania on
.
a function f(x) is defined as f(x)= 8x^2. What is f(3)?

math 
Leo,
All you need to do is substitute 3 in place of the x.

math 
Ollie,
substitute 3 for every x in f(x) and simplify.

math 
Steve,
by now you've probably done it, but watch the "" signs carefully
f(3) = 8 * (3)^2 = 8(9) = 72