Hey can you me posted picture of question

x³ - 3x² - 18x

Explanation:
Before we begin, remember the following:
xᵃ * xᵇ = xᵃ⁺ᵇ

Now, for the given:
To solve thus question, we will simply multiply each term from the first bracket by each term from the second bracket and then combine like terms to get the final answer.

This can be done as follows:
(x + 3)(x² - 6x)
x(x²) + x(-6x) + 3(x²) + 3(-6x)
x³ - 6x² + 3x² - 18x
x³ - 3x² - 18x

Hope this helps :)