Find x int and y int of the function:
2x^3-13x^2+22x-8

Question

Find x int and y int of the function: 
2x^3-13x^2+22x-8

anonymous · Answer

I know I can find them just by graphing,, but I need to know how to do it algebraically

e.mccormick · Answer

$2x^3-13x^2+22x-8 $  I am going to assume that is =0?

e.mccormick · Answer

Or =y...

e.mccormick · Answer

Factor it, set it to 0, solve each factor.  Those are the x intercepts.

e.mccormick · Answer

The y intercept is easy.  It is a gimmie.  Set x to 0.  Poof.  All x terms are gone.  What is left is the y intercept.

anonymous · Answer

i think he knows this. he wants to know how to factor a third-order polynomial.

anonymous · Answer

exactly

anonymous · Answer

I know what the answers are I don't know how to factor a third degree polynomial

e.mccormick · Answer

Ah, that is a little longer topic than I can take on when going to bed... hmmmm... Heard of the rational roots theorem? http://www.purplemath.com/modules/rtnlroot.htm They may have covered that one recently in your class, or may be about to.

anonymous · Answer

we already did im just reviewing for finals lol, but thanks!

e.mccormick · Answer

Ah, kk.  Well, that is the sort of method they normally go for.  A lot of times I just try a couple logical guesses based on the terms because most things that are meant to be factored usually have one easy one.  Once that is divided out, I can solve the rest a number of ways.  I have seen a nice method for quadratics recently, but not for 3rd order plus.

campbell_st · Answer

if you use the rational root theorem 

then the factors of 8 over the factor of 2 will give a rational root... 

so use the remainder theorem for 

f(2) just as a guess.... if it equals zero then you have a root... 

then a little division and factoring will give the other roots or intercepts.

just a thought