Question

Factor 2x4 - 20x2 - 78.



2(x2- 3)(x2- 13) *****
2(x2+ 3)(x2- 13)
2(x2- 3)(x2+ 13)
I think is right ****

Answer 1

help me @FibonacciChick666

Answer 2

I would like you to please first try and check your answer before I try the problem. You are going to do this by using the FOIL method.

Answer 3

I did that's y I asked if its right

Answer 4

alrighty good, I'm working on it right now

Answer 5

okay lol

Answer 6

ok so only one of your answers is correct. let's go through the process together.

Answer 7

First factor out the 2 to get 2(x^4-10x^2-39)
Replace any x^2 value with the variable a, so x^4 becomes a^2 because x^2 squared is x^4. You just do this to take the place of any x^2 s to make it easier, if that makes sense. So 2(a^2-10a-39). Then you can do regular factoring. 3 and -13 multiply to become -39, and 3-13=10. So The equation would become \[2(a+13)(a-3)\] Then change the a's back into x^2. So the answer is \[2(x ^{2}+3)(x ^{2}-13)\] So the answer is the second one.

Answer 8

So the first thing that we want to do is pull out any like terms. What does each term in the expression have in common?

Answer 9

x2

Answer 10

okay I need help again

Answer 11

ok, does the term (-78) contain an \[x ^{2}\]

Answer 12

idk

Answer 13

You can check your work by multiplying the factors back together using either the box method or FOIL. \[2(x ^{4}-13x ^{2}+3x ^{2}-39)\]Combine like terms to get \[2(x ^{4}-10x ^{2}-39)\]Then distribute the 2 \[2x ^{4}-20x ^{2}-78\]You know your answer is correct if it is the same as the original equation.

Answer 14

will u help me in another problem @rosedewittbukater

Answer 15

let's try a different approach. can you divide -78 by x^2 without leaving a remainder?

Answer 16

yes

Answer 17

Sure

Answer 18

okay I posted it already

Answer 19

ok so what is -78 divided by x^2 ?

Answer 20

Where did you post it

Answer 21

is it -39

Answer 22

on open questions

Answer 23

-39 is -78 divided by only 2 but think about the other terms listed do they also divide by 2?

Answer 24

idk

Answer 25

She's trying to ask what number or value can be divided out of every single part of the equation. There's no x^2 in 78 so the only common number that all of the numbers can be divided by is 2.

Answer 26

let's try a slightly simplified example if you have the equation:
\[2x+2\]

What number is common to both terms?