Here `x^3-18x^2+81x-108=0`
Let `f(x) = x^3-18x^2+81x-108`
`:. f'(x) = 3x^2-36x+81`
`x_0 = 2`
`1^(st)` iteration :`f(x_0)=f(2)=2^3-18 xx 2^2+81 xx 2-108=-10`
`f'(x_0)=f'(2)=3 xx 2^2-36 xx 2+81=21`
`x_1 = x_0 - f(x_0)/(f'(x_0))`
`x_1=2 - (-10)/(21)`
`x_1=2.47619048`
`2^(nd)` iteration :`f(x_1)=f(2.47619048)=2.47619048^3-18 xx 2.47619048^2+81 xx 2.47619048-108=-2.61310874`
`f'(x_1)=f'(2.47619048)=3 xx 2.47619048^2-36 xx 2.47619048+81=10.25170068`
`x_2 = x_1 - f(x_1)/(f'(x_1))`
`x_2=2.47619048 - (-2.61310874)/(10.25170068)`
`x_2=2.73108562`
`3^(rd)` iteration :`f(x_2)=f(2.73108562)=2.73108562^3-18 xx 2.73108562^2+81 xx 2.73108562-108=-0.67028101`
`f'(x_2)=f'(2.73108562)=3 xx 2.73108562^2-36 xx 2.73108562+81=5.05740364`
`x_3 = x_2 - f(x_2)/(f'(x_2))`
`x_3=2.73108562 - (-0.67028101)/(5.05740364)`
`x_3=2.86362023`
`4^(th)` iteration :`f(x_3)=f(2.86362023)=2.86362023^3-18 xx 2.86362023^2+81 xx 2.86362023-108=-0.16993156`
`f'(x_3)=f'(2.86362023)=3 xx 2.86362023^2-36 xx 2.86362023+81=2.51063417`
`x_4 = x_3 - f(x_3)/(f'(x_3))`
`x_4=2.86362023 - (-0.16993156)/(2.51063417)`
`x_4=2.93130495`
`5^(th)` iteration :`f(x_4)=f(2.93130495)=2.93130495^3-18 xx 2.93130495^2+81 xx 2.93130495-108=-0.04279527`
`f'(x_4)=f'(2.93130495)=3 xx 2.93130495^2-36 xx 2.93130495+81=1.25066799`
`x_5 = x_4 - f(x_4)/(f'(x_4))`
`x_5=2.93130495 - (-0.04279527)/(1.25066799)`
`x_5=2.96552287`
`6^(th)` iteration :`f(x_5)=f(2.96552287)=2.96552287^3-18 xx 2.96552287^2+81 xx 2.96552287-108=-0.01073903`
`f'(x_5)=f'(2.96552287)=3 xx 2.96552287^2-36 xx 2.96552287+81=0.62415429`
`x_6 = x_5 - f(x_5)/(f'(x_5))`
`x_6=2.96552287 - (-0.01073903)/(0.62415429)`
`x_6=2.98272861`
`7^(th)` iteration :`f(x_6)=f(2.98272861)=2.98272861^3-18 xx 2.98272861^2+81 xx 2.98272861-108=-0.00268986`
`f'(x_6)=f'(2.98272861)=3 xx 2.98272861^2-36 xx 2.98272861+81=0.31177998`
`x_7 = x_6 - f(x_6)/(f'(x_6))`
`x_7=2.98272861 - (-0.00268986)/(0.31177998)`
`x_7=2.99135604`
`8^(th)` iteration :`f(x_7)=f(2.99135604)=2.99135604^3-18 xx 2.99135604^2+81 xx 2.99135604-108=-0.00067311`
`f'(x_7)=f'(2.99135604)=3 xx 2.99135604^2-36 xx 2.99135604+81=0.15581542`
`x_8 = x_7 - f(x_7)/(f'(x_7))`
`x_8=2.99135604 - (-0.00067311)/(0.15581542)`
`x_8=2.99567595`
`9^(th)` iteration :`f(x_8)=f(2.99567595)=2.99567595^3-18 xx 2.99567595^2+81 xx 2.99567595-108=-0.00016836`
`f'(x_8)=f'(2.99567595)=3 xx 2.99567595^2-36 xx 2.99567595+81=0.07788903`
`x_9 = x_8 - f(x_8)/(f'(x_8))`
`x_9=2.99567595 - (-0.00016836)/(0.07788903)`
`x_9=2.99783745`
`10^(th)` iteration :`f(x_9)=f(2.99783745)=2.99783745^3-18 xx 2.99783745^2+81 xx 2.99783745-108=-0.0000421`
`f'(x_9)=f'(2.99783745)=3 xx 2.99783745^2-36 xx 2.99783745+81=0.03893984`
`x_10 = x_9 - f(x_9)/(f'(x_9))`
`x_10=2.99783745 - (-0.0000421)/(0.03893984)`
`x_10=2.9989186`
`11^(th)` iteration :`f(x_10)=f(2.9989186)=2.9989186^3-18 xx 2.9989186^2+81 xx 2.9989186-108=-0.00001053`
`f'(x_10)=f'(2.9989186)=3 xx 2.9989186^2-36 xx 2.9989186+81=0.01946875`
`x_11 = x_10 - f(x_10)/(f'(x_10))`
`x_11=2.9989186 - (-0.00001053)/(0.01946875)`
`x_11=2.99945927`
`12^(th)` iteration :`f(x_11)=f(2.99945927)=2.99945927^3-18 xx 2.99945927^2+81 xx 2.99945927-108=-0.00000263`
`f'(x_11)=f'(2.99945927)=3 xx 2.99945927^2-36 xx 2.99945927+81=0.00973408`
`x_12 = x_11 - f(x_11)/(f'(x_11))`
`x_12=2.99945927 - (-0.00000263)/(0.00973408)`
`x_12=2.99972963`
`13^(th)` iteration :`f(x_12)=f(2.99972963)=2.99972963^3-18 xx 2.99972963^2+81 xx 2.99972963-108=-0.00000066`
`f'(x_12)=f'(2.99972963)=3 xx 2.99972963^2-36 xx 2.99972963+81=0.00486697`
`x_13 = x_12 - f(x_12)/(f'(x_12))`
`x_13=2.99972963 - (-0.00000066)/(0.00486697)`
`x_13=2.99986481`
`14^(th)` iteration :`f(x_13)=f(2.99986481)=2.99986481^3-18 xx 2.99986481^2+81 xx 2.99986481-108=-0.00000016`
`f'(x_13)=f'(2.99986481)=3 xx 2.99986481^2-36 xx 2.99986481+81=0.00243347`
`x_14 = x_13 - f(x_13)/(f'(x_13))`
`x_14=2.99986481 - (-0.00000016)/(0.00243347)`
`x_14=2.9999324`
`15^(th)` iteration :`f(x_14)=f(2.9999324)=2.9999324^3-18 xx 2.9999324^2+81 xx 2.9999324-108=-0.00000004`
`f'(x_14)=f'(2.9999324)=3 xx 2.9999324^2-36 xx 2.9999324+81=0.00121673`
`x_15 = x_14 - f(x_14)/(f'(x_14))`
`x_15=2.9999324 - (-0.00000004)/(0.00121673)`
`x_15=2.9999662`
Approximate root of the equation `x^3-18x^2+81x-108=0` using Newton Raphson method is `2.9999662` (After 15 iterations)
`n` | `x_0` | `f(x_0)` | `f'(x_0)` | `x_1` | Update |
1 | 2 | -10 | 21 | 2.47619048 | `x_0 = x_1` |
2 | 2.47619048 | -2.61310874 | 10.25170068 | 2.73108562 | `x_0 = x_1` |
3 | 2.73108562 | -0.67028101 | 5.05740364 | 2.86362023 | `x_0 = x_1` |
4 | 2.86362023 | -0.16993156 | 2.51063417 | 2.93130495 | `x_0 = x_1` |
5 | 2.93130495 | -0.04279527 | 1.25066799 | 2.96552287 | `x_0 = x_1` |
6 | 2.96552287 | -0.01073903 | 0.62415429 | 2.98272861 | `x_0 = x_1` |
7 | 2.98272861 | -0.00268986 | 0.31177998 | 2.99135604 | `x_0 = x_1` |
8 | 2.99135604 | -0.00067311 | 0.15581542 | 2.99567595 | `x_0 = x_1` |
9 | 2.99567595 | -0.00016836 | 0.07788903 | 2.99783745 | `x_0 = x_1` |
10 | 2.99783745 | -0.0000421 | 0.03893984 | 2.9989186 | `x_0 = x_1` |
11 | 2.9989186 | -0.00001053 | 0.01946875 | 2.99945927 | `x_0 = x_1` |
12 | 2.99945927 | -0.00000263 | 0.00973408 | 2.99972963 | `x_0 = x_1` |
13 | 2.99972963 | -0.00000066 | 0.00486697 | 2.99986481 | `x_0 = x_1` |
14 | 2.99986481 | -0.00000016 | 0.00243347 | 2.9999324 | `x_0 = x_1` |
15 | 2.9999324 | -0.00000004 | 0.00121673 | 2.9999662 | `x_0 = x_1` |