question\nexpress (x + 9)^2 as a trinomial in standard form.

Explanation:

Step1: Apply binomial square formula

$$(a + b)^2 = a^2 + 2ab + b^2$$

Step2: Identify a and b

$a = x$, $b = 9$

Step3: Compute each term

$a^2 = x^2$, $2ab = 2 \cdot x \cdot 9 = 18x$, $b^2 = 9^2 = 81$

Step4: Combine terms

$x^2 + 18x + 81$

Answer:

$x^2 + 18x + 81$