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How do you factorise this completely?

Could you show me how its done?

x^3+x^2-6x ?

Could you show the steps as well I got x(x+3)(x-2) however when check i expand i get something different.
Original post by bobjon22444


I got x(x+3)(x-2).


this is exactly right :yep:
I think the answer is x(x^2+x-6), this is because everything in the brackets is being multiplied by the outside. The common factor here is x and,

x(x^2)=x^3

x(x)=x^2

x(-6)=-6x

=x^3+x^2-6x
Reply 3
Original post by Black Magic
I think the answer is x(x^2+x-6), this is because everything in the brackets is being multiplied by the outside. The common factor here is x and,

x(x^2)=x^3

x(x)=x^2

x(-6)=-6x

=x^3+x^2-6x


...it clearly says completely.

How do you factorise the quadratic x^2 + x - 6?
Original post by Zacken
...it clearly says completely.

How do you factorise the quadratic x^2 + x - 6?


True. I am no maths expert but my answer is what I would do. I think you are probably correct.
Reply 5
Original post by the bear
this is exactly right :yep:


I know but when I expand to check I get x^4+6x-6... Is there a different way to check if you get factorising right?
Reply 6
Original post by bobjon22444
Could you show me how its done?

x^3+x^2-6x ?

Could you show the steps as well I got x(x+3)(x-2) however when check i expand i get something different.


Original post by bobjon22444
I know but when I expand to check I get x^4+6x-6... Is there a different way to check if you get factorising right?



x(x+3)(x2)=x(x×x2×x+3×x2×3)=x(x2+x6)=x3+x26xx(x+3)(x-2) = x(x\times x - 2\times x + 3 \times x - 2 \times 3) = x(x^2 +x - 6) = x^3 + x^2 - 6x

Original post by Black Magic
True. I am no maths expert but my answer is what I would do. I think you are probably correct.


Look up quadratic factorisation. :smile:
(edited 8 years ago)
Reply 7
Original post by Zacken
x(x+3)(x2)=x(xx2x+3x23)=x(x2+x6)=x3+x26xx(x+3)(x-2) = x(x\cdot x - 2\cdot x + 3 \cdot x - 2 \cdot 3) = x(x^2 +x - 6) = x^3 + x^2 - 6x



Look up quadratic factorisation. :smile:


Wait what are those dots ?
Reply 8
Original post by bobjon22444
Wait what are those dots ?


Multiplication, I'll edit it and use the times symbol instead.

Edited: is that any better?
Reply 9
Original post by bobjon22444
Wait what are those dots ?


Do you know how to expand brackets

(a+b)(c+d)=a(c+d)+b(c+d)=a×c+a×d+b×c+b×d(a+b)(c+d) = a(c+d) + b(c+d) = a \times c + a \times d + b \times c + b\times d
Original post by bobjon22444
Could you show me how its done?

x^3+x^2-6x ?

Could you show the steps as well I got x(x+3)(x-2) however when check i expand i get something different.


x(x^2+x-6)... Find the common factor
x(x+3)(x-2)... Factorise the quadratic in the bracket.

You've got the correct answer....


Posted from TSR Mobile
Original post by Zacken
Do you know how to expand brackets

(a+b)(c+d)=a(c+d)+b(c+d)=a×c+a×d+b×c+b×d(a+b)(c+d) = a(c+d) + b(c+d) = a \times c + a \times d + b \times c + b\times d


I see thank you very much. Maths is starting to make a lot more sense.
Reply 12
Original post by bobjon22444
I see thank you very much. Maths is starting to make a lot more sense.


Great! Glad I could help. :-)

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