Answer: (x + 9)^2 = x^2 + 18x + 18
Explanation:
A neat trick that can help you get this answer is the box method, Draw a box with 4 smaller boxes in it. Then on the right of the box, but the first box(outside on the right) x, bottom from there, but 9. At the top of the box(first square) put x again and beside it, another 9, we do this because when a variable is with a constant inside parentheses, they can't combine, so you do what's outside the parentheses, in this case its the exponent of 2. Then we do the math, x + x is x squared, x * 9 is 9x(when you multiply a variable and constant, you can combine those), 9 + 9 is 18, then you should get x^2 + 9x + 9x + 18, next you combine "Like Terms"(same values). They only Like Terms here would be 9x and 9x, when combining Like Terms, you must only add, don't multiply, 9x + 9x would be 18x. Then you got quadratic to standard.
(x + 9)^2 ---) x^2 + 18x + 18.