9. let f(x) = x2 + 3x - 4 and g(x) = x + 5. find f(x) · g(x). (1 point)
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x3 + 3x2 + 16x - 20
x3 + 5x2 + 14x – 20
x3 + 8x2 + 11x - 20
x3 + 9x2 + 19x – 20

Hey there! My name is Maggie and I’m here to help you with your homework!
This is a polynomial exercise and it’s objective is to use the distributive propriety. In theory, it means to multiply every factor in the first polynomial by the other one.

X^2 . X = x^3
X^2 . 5 = 5x^2
3X . X = 3x^2
3X . 5 = 15x
-4 . X = -4x
-4 . 5 = -20

Now remember to add every term that has X’s with the same exponents.
So, we add 5x^2 and 3x^2 and we get 8x^2.
We do the same with 15x + (-4x) = 11x
And the answer is:

x^3+8x^2+11x-20.

I hope You’ll find my answer helpful.
Have a nice day!