# Solving for x-cubic function

x3-8x+5

## The Attempt at a Solution

I am stuck here. I tried factoring.

Related Precalculus Mathematics Homework Help News on Phys.org
SammyS
Staff Emeritus
Homework Helper
Gold Member
There's no question here.

What are you trying to do / get to ??

Sorry... solve for x

Mark44
Mentor
You can't solve for x - you don't have an equation.

x3-8x+5 is the equation

Mark44
Mentor
x3-8x+5 is the equation
This is NOT an equation. An equation ALWAYS has an = in it.

This is NOT an equation. An equation ALWAYS has an = in it.
Sorry...x3-8x+5=0

Mark44
Mentor
OK, finally an equation.

Your polynomial doesn't have any nice (i.e., rational) roots, so short of using a very complicated formula from about the 16th century, it looks to me like you need to get the root or roots by graphing the function or using some approximation technique.

What is the complete problem description?

Last edited:
Sorry about my terrible earlier posts...

The problem asks me to solve x3-8x+5=0 algebraically

heres what i have gotten to so far. Not sure if this will help me:

i made the original equation into x(x-√8)(x+√8)+5=0

Last edited:
gb7nash
Homework Helper
Sorry about my terrible earlier posts...

The problem asks me to solve x3-8x+5=0 algebraically
Did you copy the problem correctly? Are you sure it's not x2-8x+5=0? Otherwise, your problem has no answer (other than using the cubic formula).

Mark44
Mentor
Are you absolutely sure this is the equation you're supposed to solve?
x3-8x+5=0

Has your teacher shown you a technique for solving cubic equations? If not, you can't be expected to solve this one.

SammyS
Staff Emeritus
Homework Helper
Gold Member
x3-8x+5=-2

is nicer.

symbolipoint
Homework Helper
Gold Member

x3-8x+5

## The Attempt at a Solution

I am stuck here. I tried factoring.
supposed to be, x3-8x+5=0.

What course are you in? What methods and techniques have you studied so far? Do you know how many and what kind of roots this equation should have?