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# How to factorise cubic expressions?

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1. Ok so y = x^3 + x^2 - 2x

How do I do this

And x^3 - x^2

and x^3 = 9x

Basically I've used these questions because each one is different and uses different techniques

Thanks!!!!
2. Pull out common factors

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3. Have you done remainder theorem? I.e. , when , (x-y) is a factor.
4. (Original post by Atheism)
Have you done remainder theorem? I.e. , when , (x-y) is a factor.
Thats the factor theorem

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Pull out common factors

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(Original post by Atheism)
Have you done remainder theorem? I.e. , when , (x-y) is a factor.

Thats the factor theorem

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No I haven't
only x is a common factor????
Thats the factor theorem

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Sure, but the factor theorem is only a special case of the remainder theorem so it is the remainder theorem
7. (Original post by Blueray2)
No I haven't
only x is a common factor????
Then take x out and you have a quadratic to factorise
8. (Original post by TenOfThem)
Then take x out and you have a quadratic to factorise
oh so x(x^2+x-2)

then I solve x^2+x-2=0
to get 2 x brackets

and the first x is just = 0
9. (Original post by TenOfThem)
Sure, but the factor theorem is only a special case of the remainder theorem so it is the remainder theorem
That makes sense

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10. (Original post by Blueray2)
oh so x(x^2+x-2)

then I solve x^2+x-2=0
to get 2 x brackets

and the first x is just = 0
yes

remind me ... do you go to school and have a teacher or is this all you?
11. (Original post by TenOfThem)
Then take x out and you have a quadratic to factorise
Cheers I got it right Your amazing
12. since everything is in terms of x it's much easier you just pull out x and then factorize the quadratic.
13. (Original post by TenOfThem)
yes

remind me ... do you go to school and have a teacher or is this all you?
I go school, but the teacher doesn't help, he refuses to, and I get loads of H.w
but it's fine I got it right with your help
14. (Original post by Blueray2)
I go school, but the teacher doesn't help, he refuses to, and I get loads of H.w
but it's fine I got it right with your help
TenOfThem should be getting paid by your school as well as her own.
15. (Original post by BabyMaths)
TenOfThem should be getting paid by your school as well as her own.
LoL
16. (Original post by TenOfThem)
x
sorry! Didn't realise you were female I am on the app so cant see the signs!

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17. (Original post by BabyMaths)
TenOfThem should be getting paid by your school as well as her own.
I swear one day when I'm rich i'll make my own school which gives free tutoring
18. (Original post by BabyMaths)
TenOfThem should be getting paid by your school as well as her own.

(Original post by TenOfThem)
LoL

sorry! Didn't realise you were female I am on the app so cant see the signs!

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For the 2nd one I got
x^3 - x^2

= x(x^2-x)

what does (x^2-x) =
I mean in terms of x values to draw the sketchs
19. erm ....

20. (Original post by TenOfThem)
erm ....

lol yh my bad, was abt to edit that

Ok so x^2 = (x)(x)
so x = 0
and x =1
thanks I get it

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