we were given a function of y=(x-a)(x-b)(x-c) and were told to add in our own numbers i chose y=(x-8)(x+5)(x-3). can some one show me the working to get it to a cubic and then the derivative

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- Aug 25th 2008, 05:29 PMpsychosocial for lifecubic help
we were given a function of y=(x-a)(x-b)(x-c) and were told to add in our own numbers i chose y=(x-8)(x+5)(x-3). can some one show me the working to get it to a cubic and then the derivative

- Aug 25th 2008, 05:37 PMJhevon
lets say it was (x - 8)(x + 5), could you expand that?

expand the first two first, and then multiply what you got by the (x - 3). how? first multiply everything by the x and then multiply everything by the -3

when finding the derivative, all that is needed is the power rule:

and of course, if there are constants in front of the x's, you just leave them and multiply what you got by them since . here, your is

(why did you choose such big numbers? :p) - Aug 25th 2008, 06:04 PMpsychosocial for life
thanks for the help

Quote:

(why did you choose such big numbers? :p)

- Aug 25th 2008, 06:05 PMJhevon
- Aug 25th 2008, 07:30 PMpsychosocial for life
for some reason it still isnt working out right could you please show me the working out so i can workout what im doing wrong. i just cant work it out (Crying)

- Aug 25th 2008, 07:58 PMJhevon
- Aug 25th 2008, 08:07 PMpsychosocial for life
thank you again i found out what i did wrong. i got x^3-6x^2-31x-120

- Aug 25th 2008, 08:07 PMJhevon
- Aug 25th 2008, 08:09 PMpsychosocial for life
sorry miss type i got +120