Find the approximated integral value of an equation 1/x using Simpson's 1/3 rule
a = 1 and b = 2
Step value (h) = 0.25Solution:Equation is `f(x)=(1)/(x)`
`a=1`
`b=2`
The value of table for `x` and `f(x)`
| `x` | `f(x)` |
| `x_0=1` | `f(x_(0))=f(1)=1` |
| `x_1=1.25` | `f(x_(1))=f(1.25)=0.8` |
| `x_2=1.5` | `f(x_(2))=f(1.5)=0.6667` |
| `x_3=1.75` | `f(x_(3))=f(1.75)=0.5714` |
| `x_4=2` | `f(x_(4))=f(2)=0.5` |
Method-1:Using Simpsons `1/3` Rule
`int f(x) dx=(Delta x )/3 (f(x_(0))+4(f(x_(1))+f(x_(3))+f(x_(5))+...+f(x_(n-1)))+2(f(x_(2))+f(x_(4))+f(x_(6))+...+f(x_(n-2)))+f(x_(n)))`
`int f(x) dx=(Delta x )/3 [f(x_(0))+4f(x_(1))+2f(x_(2))+4f(x_(3))+f(x_(4))]`
`f(x_(0))=1`
`4f(x_(1))=4*0.8=3.2`
`2f(x_(2))=2*0.6667=1.3333`
`4f(x_(3))=4*0.5714=2.2857`
`f(x_(4))=0.5`
`int f(x) dx=0.25/3*(1+3.2+1.3333+2.2857+0.5)`
`=0.25/3*(8.319)`
`=0.6933`
Solution by Simpson's `1/3` Rule is `0.6933`
Method-2:Using Simpsons `1/3` Rule
`int f(x) dx=(Delta x )/3 (f(x_(0))+4(f(x_(1))+f(x_(3))+f(x_(5))+...+f(x_(n-1)))+2(f(x_(2))+f(x_(4))+f(x_(6))+...+f(x_(n-2)))+f(x_(n)))`
`int f(x) dx=(Delta x )/3 [(f(x_(0))+f(x_(4)))+4(f(x_(1))+f(x_(3)))+2(f(x_(2)))]`
`=0.25/3 [(1 +0.5)+4xx(0.8+0.5714)+2xx(0.6667)]`
`=0.25/3 [(1 +0.5)+4xx(1.3714)+2xx(0.6667)]`
`=0.25/3 [(1.5)+(5.4857)+(1.3333)]`
`=0.6933`
Solution by Simpson's `1/3` Rule is `0.6933`
This material is intended as a summary. Use your textbook for detail explanation.
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