solve for x
(1/15)x^3-x+1=0

Question

solve for x
(1/15)x^3-x+1=0

anonymous · Answer

good luck

precal · Answer

my professor is BC (before calculators)
I was thinking about multiplying by 15 but I am stuck

precal · Answer

@satellite73   really?

bahrom7893 · Answer

LOL

anonymous · Answer

yeah really
it is cubic
what are you going to do?  i mean you can estimate, say using newton-ralphson
but what else are you going to do ?

precal · Answer

I was thinking about synthetic division but I can't fine one zero

anonymous · Answer

because there is not a rational one

precal · Answer

I haven't learn newton-ralphson yet

anonymous · Answer

then forget it
why are you supposed to do this?  i mean without a graphing calculator?

precal · Answer

well I guess this is one that has to be solved with a calculator

anonymous · Answer

precal · Answer

No you are right, some questions require technology

anonymous · Answer

what on earth?

anonymous · Answer

be nice - read my caveat :)

precal · Answer

because the solutions don't work; sub them back in and you will not get a zero

anonymous · Answer

ok, sorry
$$x(x^2-15)=-15$$ tells you nothing

bahrom7893 · Answer

Satellite is right.

anonymous · Answer

i did that after i posted :)

anonymous · Answer

if i have 
$$ab=-15$$  then a and b can be any numbers

precal · Answer

yes satellite is right

anonymous · Answer

just says 
$$a=\frac{-15}{b}$$ pick an a, get the b