SOLUTION: f(x)=4x^3+14x-8 I need the approximate real zeros of f to the nearest thousandth.

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: f(x)=4x^3+14x-8 I need the approximate real zeros of f to the nearest thousandth.       Log On


   

Question 883955: f(x)=4x^3+14x-8
I need the approximate real zeros of f to the nearest thousandth.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
graph%28300%2C300%2C-2%2C2%2C-2%2C2%2C4x%5E3%2B14x-8+%29
Looks like the zero lies between 0 and 1.
I used Newton's method with a starting value of 0.5.
x%5Bn%2B1%5D=x%5Bn%5D-f%28x%5Bn%5D%29%2F%28%28df%2Fdx%29%28x%5Bn%5D%29%29
with
f=4x%5E3%2B14x-8
df%2Fdx=12x%5E2%2B14
x=0.529107