How to Solve a Nonlinear Equation Using Newton's Method?

[TyErd]

Homework Statement

I've attached the question

Homework Equations

x(n+1) = x(n) - f(x(n)) / f '(x(n))

The Attempt at a Solution

2.5x^3 =2cos(x) + 8
okay so this has to be in the form of f(x) = ... but there is no y variable for me to make it into that form. once I've gotten it into that form, it should be easy but its the manipulation that's got me stuck.
0 =2cos(x) + 8 - 2.5x^3

 

[Bohrok]

You want it in the form of f(x) = 0, and you have the equation 0 = 2cos(x) + 8 - 2.5x^3, so f(x) = 2cos(x) + 8 - 2.5x^3

 

[TyErd]

oh i didnt know that, i got an answer of x1=1.508306, x2=1.48451 and x3=1.48416 looks right