Question

One of the factors of 6x^3 - 864x is

4

x2

x + 12

x - 8

Answer 1

@ganeshie8

Answer 2

I need teaching xD

Answer 3

so how can I find a factor and what is a factor

Answer 4

first see that, it has two terms.
can u pull out something common ?

Answer 5

They both have x but one is x^3

Answer 6

yes, they have x in common
also they have 6 in common

Answer 7

pull out the common factor 6x :-

6x^3 - 864x

6x (x^2 - 144)

Answer 8

fine ?

Answer 9

o_O I didn't figure 6 would be a common but alright works for me :D

Answer 10

lol how' 864 go to 144?

Answer 11

wats 6*144 ? :)

Answer 12

oh I see... its 864

Answer 13

ok so now what

Answer 14

6x^3 - 864x

6x (x^2 - 144)

Answer 15

is 144 a perfect square ?

Answer 16

12*12 = 144, so yes its a perfect square :-

6x^3 - 864x

6x (x^2 - 144)

6x(x^2-12^2)

Answer 17

yeah I think

Answer 18

next use the identity :-

a^2-b^2 = (a+b)(a-b)

Answer 19

wat do u get ?

Answer 20

I'm not sure how to input 6x(x^2-12^2) into that equation

Answer 21

\(a^2-b^2 = (a+b)(a-b)\)

so,

\(x^2-12^2 = ?\)

Answer 22

-12x^2?

Answer 23

let me show u once, then u wil see how to to :-

\(a^2-b^2 = (a+b)(a-b)\)

so,

\(x^2 - 12^2 = (x+12)(x-12)\)

Answer 24

now, get back to oiur original problem :-

6x^3 - 864x

6x (x^2 - 144)

6x(x^2-12^2)

6x(x+12)(x-12)

Answer 25

see if it makes some sense

Answer 26

so it would be 6x^3 - 12^3 = (x+12)(x-12)?

Answer 27

wat happened to the 6x before it ?

Answer 28

6x^3 - 12^3 = 6x(x+12)(x-12)

Answer 29

we say : 6, x, x+12 and x-12 are the factors

Answer 30

look at ur options and see they have any of these

Answer 31

man this factor stuff is confusing lol

Answer 32

x + 12 is an option

Answer 33

Alright I think I got it :)

Answer 34

we need to remember few identities like the one we have used in this :-
\(a^2-b^2 = (a+b)(a-b)\)

Answer 35

oly that identity i guess, if u are able to identify that wid ease,
then its all easy :)

Answer 36

yeah, can you lend me a hand on a couple more? I want to make sure I get the identity formula down :)

Answer 37

okay sure :)

Answer 38

thanks