Step by step
The question
Question: for which x is f(x) = 1 in this table of f?
f(x) = 1 x = ?
1 Look at the table
The table shows f.
Each x on top has its f(x) right under it.
For example, f of −2 is 4.
x: top row
f(x): right under its x
2 Find where f(x) = 1
This time we know f(x): it is 1.
We look for the x.
f(x) = 1 → 1 in the f(x) row → x = ?
Careful!
Do not stop at the first x.
The table can have the same f(x) more than once.
Careful: look for every x: f(x) can be 1 more than once
Find 1 in the f(x) row.
Right above it: x = −1.
1 is in the f(x) row again.
Right above it: x = 1.
So x = −1 or x = 1.
x = −1 or x = 1
3 Check
Let's check: put the x back.
Under x = −1 the table has 1.
column: x = −1, f(x) = 1
And under x = 1 the table has 1.
So the answer is right!
column: x = 1, f(x) = 1
Let's look back.
First: look at the table.
Then: find where f(x) = 1.
Last: check.
Answer
x = −1 or x = 1