Question

Find a cubic function with the given zeros.

Square root of seven., -Square root of seven., -4

Answer 1

putting all of our zeros together, we get:

f(x) = (x+sqrt7)(x-sqrt7)(x+4)

all you need to do is expand that by multiplying everything out

Answer 2

but how

Answer 3

start with (x+sqrt7)(x-sqrt7)

then use the difference if squares formula

(x+A)(x-A) = x^2-A^2

Answer 4

x^2-sqrt7^2
x^2-7

Answer 5

right?

Answer 6

good, now we tack on (x+4)

(x^2-7)*(x+4)

use foil to expand that

Answer 7

x^3+4x^2-7x-28

Answer 8

like that right?

Answer 9

excellent! now take a look at your answer choices and see which one matches

Answer 10

thank you