Question

Find the Product: (x+9i)^2

Answer 1

x² + 18xi - 81

Explanation:

FOIL - First, Outside, Inside, Last

Step 1: Write out expression

(x + 9i)²

Step 2: Expand

(x + 9i)(x + 9i)

Step 3: FOIL

F - x²

O - 9xi

I - 9xi

L - 81i²

Step 4: Combine

x² + 18xi + 81i²

Step 5: Simplify

i² = -1

x² + 18xi + 81(-1)

x² + 18xi - 81