Find the approximated integral value of an equation 1/x using Trapezoidal 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 Trapezoidal Rule
`int f(x) dx=(Delta x )/2 (f(x_(0))+2(f(x_(1))+f(x_(2))+f(x_(3))+...+f(x_(n-1)))+f(x_(n)))`
`int f(x) dx=(Delta x )/2 [f(x_(0))+2f(x_(1))+2f(x_(2))+2f(x_(3))+f(x_(4))]`
`f(x_(0))=1`
`2f(x_(1))=2*0.8=1.6`
`2f(x_(2))=2*0.6667=1.3333`
`2f(x_(3))=2*0.5714=1.1429`
`f(x_(4))=0.5`
`int f(x) dx=0.25/2*(1+1.6+1.3333+1.1429+0.5)`
`=0.25/2*(5.5762)`
`=0.697`
Solution by Trapezoidal Rule is `0.697`
Method-2:Using Trapezoidal Rule
`int f(x) dx=(Delta x )/2 (f(x_(0))+2(f(x_(1))+f(x_(2))+f(x_(3))+...+f(x_(n-1)))+f(x_(n)))`
`int f(x) dx=(Delta x )/2 [f(x_(0))+f(x_(4))+2(f(x_(1))+f(x_(2))+f(x_(3)))]`
`=0.25/2 [1 +0.5 + 2xx(0.8+0.6667+0.5714)]`
`=0.25/2 [1 +0.5 + 2xx(2.0381)]`
`=0.25/2 [1 +0.5 + 4.0762]`
`=0.697`
Solution by Trapezoidal Rule is `0.697`
This material is intended as a summary. Use your textbook for detail explanation.
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