#1

I'm simplifying rational expressions and don't know how to do this one.

x^3 + 3x^2 - 2x - 6

over

x^3 + 27

I need the steps on how to do it.

x^3 + 3x^2 - 2x - 6

over

x^3 + 27

I need the steps on how to do it.

*Last edited by carrotcake at Mar 26, 2009,*

#2

Maths question?

Maths thread.

Maths thread.

#3

use long division

#4

wow your asking the pit??!?!?! They'd give you an answer like "tats teh nubmer of tymes i didd uur momm!!!ahahahahahahahahaha". In other words don't ask the pit math stuff lol.

#5

I'm simplifying rational expressions and don't know how to do this one.

x^3 + 3x^2 - 2x - 6

over

x^3 + 27

I need the steps on how to do it.

i think first thing you have to do is cancel out the x^3 on the top and bottom because when u have exponents as a fraction, you have to subtract so that cancels out. than u hav to simplify -6 over 27 which gives you -2 over 9. so im pretty sure the answer is:

3x^2 - 2x - 6

over

9

#6

SHEdit: The above post won't work.

+1 to long division. You'll do this:

x^3 + 3x^2 - 2x - 6

------------------------------------------

x^3 + 0x^2 + 0x + 27

I'm simplifying rational expressions and don't know how to do this one.

x^3 + 3x^2 - 2x - 6

over

x^3 + 27

I need the steps on how to do it.

+1 to long division. You'll do this:

x^3 + 3x^2 - 2x - 6

------------------------------------------

x^3 + 0x^2 + 0x + 27

#7

i think first thing you have to do is cancel out the x^3 on the top and bottom because when u have exponents as a fraction, you have to subtract so that cancels out. than u hav to simplify -6 over 27 which gives you -2 over 9. so im pretty sure the answer is:

3x^2 - 2x - 6

over

9

so wrong.....you can only cancel multiplied terms........try again

#8

x^3 + 3x^2 - 2x - 6

-----------------------

x^3 + 27

Factor each.

(x^2 - 2)

----------------

(x^2 - 3x + 9)

Or something like that, I'm sorta lolies right now, but yeah, do it that way.

-----------------------

x^3 + 27

Factor each.

(x^2 - 2)

----------------

(x^2 - 3x + 9)

Or something like that, I'm sorta lolies right now, but yeah, do it that way.

#9

so wrong.....you can only cancel multiplied terms........try again

i thought tht since its x^3 over x^3 you have to subtract and tht gives u x^0 which you cant have so it cancels out

#10

Cross out the two x^3

Then you should be able to simplify the 3x^2 - 2x - 6, though I forget how.

-b +/- sqrt(b^2 - 4ac)

over

2a

Maybe?

Then you should be able to simplify the 3x^2 - 2x - 6, though I forget how.

-b +/- sqrt(b^2 - 4ac)

over

2a

Maybe?

#11

i thought tht since its x^3 over x^3 you have to subtract and tht gives u x^0 which you cant have so it cancels out

You don't. You have essentially this:

(x^3 - stuff)

------------------

(x^3 + 27)

Since those aren't the same, you can't factor anything. And since they're added, as opposed to multiplied, you can't divide things out.

#12

wow your asking the pit??!?!?! They'd give you an answer like "tats teh nubmer of tymes i didd uur momm!!!ahahahahahahahahaha". In other words don't ask the pit math stuff lol.

Can't be bothered to help OP, but that post is disgustingly stupid. There's a whole thread dedicated to Math Help and there's physics and chemistry ones too.

#13

i thought tht since its x^3 over x^3 you have to subtract and tht gives u x^0 which you cant have so it cancels out

Still wrong... if it was say (x^3)(9) over (x^3)(3x^2) then you could cancel because they are multiplied.

But long division is what I would use. You would get an answer of one and a fraction I think... hold on and I'll do it.

#14

the answer is x^2 -2 / x^2 - 3x + 9

#15

the answer is x^2 -2 / x^2 - 3x + 9

That's what I got!

#16

the answer is x^2 -2 / x^2 - 3x + 9

"simplified"

#17

the answer is x^2 -2 / x^2 - 3x + 9

How do you get that?

TS: I ended up getting 1 + [(3x^2-2x-33)over(x^3 +27)] after long division.

#18

yea but there's those people who go on the pit to piss people off and be funny so thats what i was expecting lol but i guess not.Can't be bothered to help OP, but that post is disgustingly stupid. There's a whole thread dedicated to Math Help and there's physics and chemistry ones too.

#19

"simplified"

Simplified means fully factored, in this sort of math anyways, and you can't factor that down anymore.

#20

Simplified means fully factored, in this sort of math anyways, and you can't factor that down anymore.

I know this. It's just always been funny to me.

#21

Simplified means fully factored, in this sort of math anyways, and you can't factor that down anymore.

Yeah man I see what you are saying, I don't get the point of attempting to break it down any more considering all long division does is change the form and not really the polynomial itself.

#22

How do you get that?

TS: I ended up getting 1 + [(3x^2-2x-33)over(x^3 +27)] after long division.

(x^3 + 3x^2) (- 2x - 6)

-----------------------

x^3 + 27

1) take out an x^2 from the first one

x^2(x + 3)

2) take out a -2 from the second

-2(x + 3)

So on the top you have

(x^2 - 2)(x + 3)

---------------------

3) factor the trinomial

(x + 3)(x^2 - 3x + 9)

so it's (x^2 - 2)(x+3)

-------------------

(x+3)(x^2 - 3x + 9)

The (x+3) cancel out, so

(x^2 - 2)

----------

(x^2 - 3x + 9)

Numerator and denominator are both fully factored.