Question

find the zeros of the function
f(x) = 4x3 - 12x2 - 40x

Answer 1

Any ideas?

Answer 2

not really the choices I have
-5 and 2

5 and -2

0, 5, and -2

0, -5, and 2

Answer 3

@skullpatrol Do you have this?

Answer 4

@Paynesdad You can take it pal :)

Answer 5

Laren the best bet is to try to factor if you can... always start by looking for common factors.

Answer 6

$$\Huge 4x^3 - 12x^2 - 40x$$

Answer 7

Remember to find zeros you set the function = 0 and solve for x ... right @lauren9695

Answer 8

yes

Answer 9

So the equation is \[4x^3-12x^2-40x=0\] Do you see any common factors in the left hand side?

Answer 10

@lauren9695

Answer 11

yes theyre all by a common factor of 4

Answer 12

Ok and something else too

Answer 13

ummm I cant think of anything else

Answer 14

Well don't just think about numbers consider variables too.

Answer 15

ohhh they have a variable of x

Answer 16

Right so go ahead an factor the left side and show me what you have.

Answer 17

@lauren9695

Answer 18

wouldn't you the quadratic formula

Answer 19

You can't yet because it is not a quadratic equation.... just factor the 4x out first and show me what you have ... we can go from there.

Answer 20

@lauren9695 Hello...I will be leaving soon so I need you to respond a little quicker if you want my help.

Answer 21

sorry my computer froze on me and if you factor out the 4x you would 3x^2+10x

Answer 22

No there would still be three terms...What is left when you factor 4x^2 out of the 4x^3 term?

Answer 23

oh 4x

Answer 24

No if you factor 4x out of 4x^3 you will not be left with 4x ...try again.

Answer 25

wouldn't it be x^3

Answer 26

Not if you factored out an x too!

Answer 27

$$\Huge 4x^3 - 12x^2 - 40x$$

Answer 28

\[4x^3-12x^2-40x=4x\left(??-3x-10\right)\]

Answer 29

Notice when I factored I didn't just lose or get rid of the 4x ... it just came out infront of the parentheses... but what is the ?? term @lauren9695