factorising quadratics

[jennymac]

Please can somebody help me Can you work out
x cubed - 2x cubed - 11x - 12.

I would like the working out as well please.

Thank you

[EDLEE]

as asked: -x(x squared+11)-12 seems to be as far as it can be factored. if you meant to ask for the factors of
x cubed-2x square-11x-12 then subtact 12
(xcubed-2xsquared-11x)-12 then divide the expression within paretheses by -x
-x(xsquared+2x+11)-12
-x((xsquared+2x+1)+10))-12
-x((x+1)(x+1)+10))-12 This is as far as I can take it. Perhaps others can help you more. Just remember that there may be other factors that may give the same answer , just as the number 12 can be factored by (3)(4) or (2)(6) or (1)(12) with each set of figures being both neg or pos . The answer remains.
I hope I haven't confused the issue more.

[Peter Pedant]

come on Jenny if you want us to do your prepyou have to copy it in correctly
also telling us the level could be a help

Assume you are still at Skool, so the factors are likely to be whole numbers

have youdone the factorisaiton theorem ? if x-1 is a factor then putting in x=1 into the expresison should give zero,

I think it might

then you have to do the long division - honestly you are just gonna have to read the book and do it.

so you then get a expresion like (x-1)(x2 -11x +12)

and the last expression factorises by sight to (x-12)(x+1) I think and so the whole is

x-1 x+1 X-12 with brackets around them all

and if you multiply it out, you dont get the ecpression above because in your espression there are two many cubes and one should bea square
and also at least one fo the signs is wrong

butanyway that is how you do it.

[jennymac]

Thanks for the replies. Peter I am nearly sixty and when I was in school we were still working with slates and chalk, if we reached our 12 times table we were the lucky ones.

I thank you for your time to answer but please not everyone knows as much as you.