Question 736559
<pre>
Learn this rule:  (A + B)² = A² + 2AB + B²

In your problem

                  (9b + 1)²

comparing that with the above substitute 9b for A and 1 for B

                  (9b + 1)² = (9b)² + 2(9b)(1) + (1)²
                            = 81b² + 18b + 1

Edwin</pre>