Question

Soo confused on how to factor this:
(𝑥) = 𝑥^3 + 6𝑥^2 − 13𝑥 − 42

Answer 1

Is that supposed to be

f(x) = x^3 + 6x^2 − 13x − 42

or

x = x^3 + 6x^2 − 13x − 42

Answer 2

@TheSmartOne The 2nd one.

Answer 3

Subtract x on both sides first

Answer 4

@TheSmartOne
So It would be like 0=x^3+6x^2-12x-42

Answer 5

-13x - x =

-x(13 + 1) = -x(14) = -14x

So, it should be -14x not -12x.

Do you understand? :)

Answer 6

@TheSmartOne
Ohh Okay! Yeah I understand. Thanks!

Answer 7

Now, we should have:

x^3 + 6x^2 - 14x - 42 = 0

And it cannot be factored

Answer 8

Can't is such a brash word

Answer 9

From the beginning x^3+6x^2-13x-42
Try picking out a factor of 42 and incorporating x

Answer 10

Clue: try x+2

Answer 11

Just about anything can be factored.

Answer 12

f(x) = x^3 + 6x^2 − 13x − 42 does factor over the set of Integers.

Answer 13

x^3 + 6x^2 − 13x − 42 = (x + 7) * (x^2 - x - 6)

= (x + 7) * (x - 3) * (x + 2)

@JBBADsunsaregrreat

Look at this and see if you think it is correct.

Answer 14

That's why I asked in my first reply if he meant x or f(x). :P

Answer 15

@Directrix
Yeah I think that is correct! Thanks so much I was getting really frustrated haha

Answer 16

@Directrix
If you can, can you show me how to start the problem to come to that answer?

Answer 17

@TheSmartOne Sorry must've made a mistake!

Answer 18

@JBBADsunsaregrreat

When you copied and pasted the problem, the lead "f" that goes with the (x) to be f(x) was deleted.

The posted problem looked like this: x = x^3 + 6x^2 − 13x − 42

That is different from f(x) = x^3 + 6x^2 − 13x − 42.

Always look back and check the problem you are about to post after the copy and paste procedure.

Answer 19

@JBBADsunsaregrreat

I began by using the Rational Root Theorem.