b3ta.com board
You are not logged in. Login or Signup
Home » Messageboard » XXX » Message 9725227 (Thread)

# If f(x) = x^2 + 2, find the sum and difference of the roots (solutions) for the equation: f(f(x) + 3 f(x) = xf(x) + f(x)
edit: Quiet at the back, k3b/-\b
(I helped save b3ta! Dixipoos Bye Bye Blackbird, Mon 5 Oct 2009, 12:19, archived)
# I'm still looking for the trick to do it...
ed: you missed a bracket...
(k3b/-\b Peace man., Mon 5 Oct 2009, 12:27, archived)
# Have you solved it yet?
(I helped save b3ta! Barbarossa is not my real name, Mon 5 Oct 2009, 12:51, archived)
# nup :( got the sum of roots, can't figure out the easy way to the difference.
ed: just cheated. it goes complex, which was giving me such a pain in the arse. ed, ed: i'm a dope...the difference in roots will change if the difference is taken in a different order :(

assuming obviously I have the bracket in the right spot...ed again: no the question is probably crap.
(k3b/-\b Peace man., Mon 5 Oct 2009, 12:55, archived)
# So what's the answer, brainiac?
(I helped save b3ta! Barbarossa is not my real name, Mon 5 Oct 2009, 13:49, archived)
# 42!
yay
(Canazza is mostly listening to Yes, Mon 5 Oct 2009, 13:54, archived)
# I can get a sum of the four roots and the differences between the conjugate pairs of roots.
Sum = 0.0625
Difference of pair 1 (-0.110348 ± 1.4099i) = 2.8198i
Pair 2 (0.141598 ± 1.40711i) = 2.81422i

I suspect I've taken this a little too seriously.
(I helped save b3ta! deathsquirrel Oh dear., Mon 5 Oct 2009, 16:40, archived)