Home > Numerical methods > Roots of Non-Linear Equation > Secant method example

5. Secant method example ( Enter your problem )
  1. Algorithm & Example-1 `f(x)=x^3-x-1`
  2. Example-2 `f(x)=2x^3-2x-5`
  3. Example-3 `x=sqrt(12)`
  4. Example-4 `x=root(3)(48)`
  5. Example-5 `f(x)=x^3+2x^2+x-1`

4. Example-4 `x=root(3)(48)`





Find `root(3)(48)` using Secant method

Solution:
Let `x=48^(1/3)`

`:.x^3=48`

`:.x^3-48=0`

i.e. `f(x)=x^3-48`

Here
`x`01234
`f(x)`-48-47-40-2116



`1^(st)` iteration :

`x_0 = 3` and `x_1 = 4`

`f(x_0) = f(3) = -21` and `f(x_1) = f(4) = 16`

`:. x_2 = x_0 - f(x_0) * (x_1 - x_0)/(f(x_1) - f(x_0))`

`x_2 = 3 - (-21) * (4 - 3)/(16 - (-21))`

`x_2 = 3.5676`

`:. f(x_2)=f(3.5676)=3.5676^3-48=-2.5936`


`2^(nd)` iteration :

`x_1 = 4` and `x_2 = 3.5676`

`f(x_1) = f(4) = 16` and `f(x_2) = f(3.5676) = -2.5936`

`:. x_3 = x_1 - f(x_1) * (x_2 - x_1)/(f(x_2) - f(x_1))`

`x_3 = 4 - 16 * (3.5676 - 4)/(-2.5936 - 16)`

`x_3 = 3.6279`

`:. f(x_3)=f(3.6279)=3.6279^3-48=-0.2513`


`3^(rd)` iteration :

`x_2 = 3.5676` and `x_3 = 3.6279`

`f(x_2) = f(3.5676) = -2.5936` and `f(x_3) = f(3.6279) = -0.2513`

`:. x_4 = x_2 - f(x_2) * (x_3 - x_2)/(f(x_3) - f(x_2))`

`x_4 = 3.5676 - (-2.5936) * (3.6279 - 3.5676)/(-0.2513 - (-2.5936))`

`x_4 = 3.6344`

`:. f(x_4)=f(3.6344)=3.6344^3-48=0.0047`


`4^(th)` iteration :

`x_3 = 3.6279` and `x_4 = 3.6344`

`f(x_3) = f(3.6279) = -0.2513` and `f(x_4) = f(3.6344) = 0.0047`

`:. x_5 = x_3 - f(x_3) * (x_4 - x_3)/(f(x_4) - f(x_3))`

`x_5 = 3.6279 - (-0.2513) * (3.6344 - 3.6279)/(0.0047 - (-0.2513))`

`x_5 = 3.6342`

`:. f(x_5)=f(3.6342)=3.6342^3-48=0`


Approximate root of the equation `x^3-48=0` using Secant method is `3.6342` (After 4 iterations)

`n``x_0``f(x_0)``x_1``f(x_1)``x_2``f(x_2)`Update
13-214163.5676-2.5936`x_0 = x_1`
`x_1 = x_2`
24163.5676-2.59363.6279-0.2513`x_0 = x_1`
`x_1 = x_2`
33.5676-2.59363.6279-0.25133.63440.0047`x_0 = x_1`
`x_1 = x_2`
43.6279-0.25133.63440.00473.63420`x_0 = x_1`
`x_1 = x_2`







This material is intended as a summary. Use your textbook for detail explanation.
Any bug, improvement, feedback then Submit Here





Share this solution or page with your friends.
 
 
Copyright © 2026. All rights reserved. Terms, Privacy
 
 

.