Answer:

Step-by-step explanation:
I assume that you need simplification of the given expression.
The given expression is:

Using distributive property and multiplying 2 inside the parenthesis and 1 inside the other parenthesis. This gives,

Therefore,
is equal to:

Now, combining like terms using the commutative property of addition, we get:

Therefore, the simplified form is 
(9x - 1)² = <em>81x² - 18x + 1</em>
You put the bar over the first number after the decimal