Question

Check three of my answers and help with one question!?
Question #1: multiply (x + 2) (3x^2 - 4x + 5)
My answer: My answer: 3x^3 + 2x^2 - 3x + 10.
Question #2: Find the product of (x^2 - 2x - 2) (3x^2 + 4x - 1)
My answer: 3x^4 - x^3 - 16x^2 - 10x + 3
Question #3: Multiply (b + 3) (b^2 + 2b + 1)
My answer: b^3 + 6b^2 + 7b + 3.
Question #4: A triangle has a length of 6a2c and a width of 2a3 – 3ac + 1. Write and simplify an expression for the area of the triangle.
I need help with that one. Thanks in advance.