Answer:
9x(2x + 1)
Explanation:
Looking at the two terms, notice that you can write the first term as:
18x² = 9x * 2x
Then, we can see that the first term and second term both have 9x in them. That means 9x is a common factor, so we can take it out from both of them ("take it out" basically means "divide"):
18x² + 9x = 9x * 2x + 9x = 9x * (2x + 1)
Thus, the factored form is 9x(2x + 1).
Hope this helps!