Solve f(x) = x^2, f(5)

Step by step, with the reason for every step · Functions · Algebra 2

Step by step

Question: find f(5) for f(x) = x².

f(x) = x²

f(x) is read "f of x".

It is a rule, called a function.

A number goes in for x.

The rule gives one answer out.

f(x) = "f of x"

x goes in → an answer comes out

f(5) means: put 5 in place of every x.

Every x becomes 5.

f(5) = 5²

5² means 5 times 5.

5² = 5 × 5 = 25

That is 25.

f(5) = 25

So f(5) = 25.

Let's look back.

First: put the number in.

Last: work out the power.

Answer

f(5) = 25

Try this one yourself, then check:

f(x) = x², find f(4)

Show the answer

f(4) = 16