Question

When a problem asks for f(5), what is it asking for?

A. the value of f(x) when x = 5
B. the value of x when f(x) = 5
C. the product of f(x) and 5
D. the fifth letter of the alphabet

Answer 1

A. the value of f(x) when x = 5

Answer 2

Here we have this function f(5)

Suppose the original function was f(x).

Now if we have to find the value of the function f(x) when we are given x=5, then we replace the x by 5.

So the function becomes f(5) at x=5.

For example:

If we have a function,

`f(x) = 7x+9`

and we are to find value of this function at x=2,

then we replace the x by 2 everywhere in the function,

`f(2) = 7(2)+9`

So this is how it works.

Answer: When a problem asks for f(5), it is asking for value of the function f(x) when x=5. Option A. is correct choice.