Find the approximated integral value of an equation 1/x using Weddle's rule
a = 1 and b = 2
Interval n = 6Solution:Equation is `f(x)=(1)/(x)`
`a=1`
`b=2`
`Delta x =(b-a)/n=(2 - 1)/6=0.1667`
The value of table for `x` and `f(x)`
| `x` | `f(x)` |
| `x_0=1` | `f(x_(0))=f(1)=1` |
| `x_1=1.1667` | `f(x_(1))=f(1.1667)=0.8571` |
| `x_2=1.3333` | `f(x_(2))=f(1.3333)=0.75` |
| `x_3=1.5` | `f(x_(3))=f(1.5)=0.6667` |
| `x_4=1.6667` | `f(x_(4))=f(1.6667)=0.6` |
| `x_5=1.8333` | `f(x_(5))=f(1.8333)=0.5455` |
| `x_6=2` | `f(x_(6))=f(2)=0.5` |
Method-1:Using Weddle's Rule
`int f(x) dx=(3Delta x )/10 [(f(x_(0))+5f(x_(1))+f(x_(2))+6f(x_(3))+f(x_(4))+5f(x_(5))+f(x_(6)))+(f(x_(6))+5f(x_(7))+f(x_(8))+6f(x_(9))+f(x_(10))+5f(x_(11))+f(x_(12)))+...]`
`int f(x) dx=(3Delta x )/10 [(f(x_(0))+5f(x_(1))+f(x_(2))+6f(x_(3))+f(x_(4))+5f(x_(5))+f(x_(6)))]`
`f(x_(0))=1`
`5f(x_(1))=5*0.8571=4.2857`
`f(x_(2))=0.75`
`6f(x_(3))=6*0.6667=4`
`f(x_(4))=0.6`
`5f(x_(5))=5*0.5455=2.7273`
`f(x_(6))=0.5`
`int f(x) dx=(3xx0.1667)/10*[(1+4.2857+0.75+4+0.62.7273+0.5)]`
`=(3xx0.1667)/10*(13.863)`
`=0.6931`
Solution by Weddle's Rule is `0.6931`
Method-2:Using Weddle's Rule
`int f(x) dx=(3Delta x )/10 [(f(x_(0))+5f(x_(1))+f(x_(2))+6f(x_(3))+f(x_(4))+5f(x_(5))+f(x_(6)))+(f(x_(6))+5f(x_(7))+f(x_(8))+6f(x_(9))+f(x_(10))+5f(x_(11))+f(x_(12)))+...]`
`int f(x) dx=(3Delta x )/10 [(f(x_(0))+5f(x_(1))+f(x_(2))+6f(x_(3))+f(x_(4))+5f(x_(5))+f(x_(6)))]`
`=(3xx0.1667)/10 [(1 + 5xx0.8571 + 0.75 + 6xx0.6667 + 0.6 + 5xx0.5455 + 0.5)]`
`=(3xx0.1667)/10 [13.863]`
`=0.6931`
Solution by Weddle's Rule is `0.6931`
This material is intended as a summary. Use your textbook for detail explanation.
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