Question

PLEASE HELP!!!

Let f(x) = x2 + 3x - 4 and g(x) = x + 5. Find f(x) • g(x).

Answer 1

a) x3 + 3x2 + 16x - 20
b) x3 + 5x2 + 14x - 20
c) x3 + 8x2 + 11x - 20
d) x3 + 9x2 + 19x - 20

Answer 2

So, you just multiply the functions, right?
Let's get to it :)
\[\Large (x^2 +3x - 4)(x+5)\]

Answer 3

Could you simplify this?

Answer 4

Okay, hint, we could distribute the entire \(\large (x^2 + 3x- 4)\) over the \(\large (x+5)\)
Thus giving us...
\[\Large x(x^2 + 3x -4)+ 5(x^2 + 3x - 4)\]
And now, just two more distributions and then combining like terms :)

Answer 5

to bad i cant show you what i worked out... i did it on paper

Answer 6

Well, you could tell me what you did :)

Answer 7

final answer i got was a after combining like terms. a) x3 + 3x2 + 16x - 20

Answer 8

Well, unfortunately, that's not the correct answer :)

Answer 9

Let's find out together what IS the correct answer, shall we? :)
Come now...
Distribute the x over the terms inside the parentheses.
\[\Large \color{red}x\color{green}{(x^2 + 3x -4)}+ 5(x^2 + 3x - 4)\]

Answer 10

oh i didnt distriubute

Answer 11

So, now you can distribute, what becomes of that coloured bit? :)

Answer 12

ya bro sorry im lost

Answer 13

Distribute?
Example...
\[\Large \color{red}{2x^2}\color{green}{(x - 7)}\]
You just multiply the one term outside with EACH AND EVERY term inside, like...
\[\Large = \color{red}{2x^2}\cdot \color{green}x \ \ - \ \ \color{red}{2x^2}\cdot\color{green}{7}\]\[\Large = \color{blue}{2x^3 - 14x^2}\]

Answer 14

thanks bro! i got it the answer is c) x3 + 8x2 + 11x - 20