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3. Newton Raphson 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`

1. Algorithm & Example-1 `f(x)=x^3-x-1`





Algorithm
Newton Raphson method Steps (Rule)
Step-1: Find points `a` and `b` such that `a < b` and `f(a) * f(b) < 0`.
Step-2: Take the interval `[a, b]` and
find next value `x_0 = (a+b)/2`
Step-3: Find `f(x_0)` and `f'(x_0)`
`x_1 = x_0 - f(x_0)/(f'(x_0))`
Step-4: If `f(x_1) = 0` then `x_1` is an exact root,
else `x_0 = x_1`
Step-5: Repeat steps 3 and 4 until `f(x_i) = 0` or `|f(x_i)| <= "Accuracy"`

Example-1
1. Find a root of an equation `f(x)=x^3-x-1` using Newton Raphson method

Solution:
Here `x^3-x-1=0`

Let `f(x) = x^3-x-1`

`:. f'(x) = 3x^2-1`

Here
`x`012
`f(x)`-1-15



Here `f(1) = -1 < 0 and f(2) = 5 > 0`

`:.` Root lies between `1` and `2`

`x_0 = (1 + 2)/2 = 1.5`


`1^(st)` iteration :

`f(x_0) = f(1.5) = 0.875`

`f'(x_0) = f'(1.5) = 5.75`

`x_1 = x_0 - f(x_0)/(f'(x_0))`

`x_1 = 1.5 - (0.875)/(5.75)`

`x_1 = 1.34783`


`2^(nd)` iteration :

`f(x_1) = f(1.34783) = 0.10068`

`f'(x_1) = f'(1.34783) = 4.44991`

`x_2 = x_1 - f(x_1)/(f'(x_1))`

`x_2 = 1.34783 - (0.10068)/(4.44991)`

`x_2 = 1.3252`


`3^(rd)` iteration :

`f(x_2) = f(1.3252) = 0.00206`

`f'(x_2) = f'(1.3252) = 4.26847`

`x_3 = x_2 - f(x_2)/(f'(x_2))`

`x_3 = 1.3252 - (0.00206)/(4.26847)`

`x_3 = 1.32472`


`4^(th)` iteration :

`f(x_3) = f(1.32472) = 0`

`f'(x_3) = f'(1.32472) = 4.26463`

`x_4 = x_3 - f(x_3)/(f'(x_3))`

`x_4 = 1.32472 - (0)/(4.26463)`

`x_4 = 1.32472`


Approximate root of the equation `x^3-x-1=0` using Newton Raphson method is `1.32472`

`n``x_0``f(x_0)``f'(x_0)``x_1`Update
11.50.8755.751.34783`x_0 = x_1`
21.347830.100684.449911.3252`x_0 = x_1`
31.32520.002064.268471.32472`x_0 = x_1`
41.3247204.264631.32472`x_0 = x_1`





This material is intended as a summary. Use your textbook for detail explanation.
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