Integration by Parts using Tabular Approach
Given the integral:
∫ xsin(x) dx
We’ll use the tabular method to solve it:
- Choose Functions:
- u = x
- dv = sin(x) dx
- Create a Table:
- Apply Signs and Multiply Diagonally:
- First row: (+) × (xsin(x)) = xsin(x)
- Second row: (-) × (1 × -cos(x)) = cos(x)
- Third row: (+) × (0 × -sin(x)) = 0
- Fourth row: (-) × (0 × cos(x)) = 0
- Final Result:
For the table, alternate between differentiating u and integrating dv. Start by listing u, its successive derivatives, and dv, its successive integrals:
u | dv |
---|---|
x | sin(x) |
1 | -cos(x) |
0 | -sin(x) |
0 | cos(x) |
Now, apply alternating signs down the table. Multiply the terms diagonally and add them up:
(+) × (xsin(x)) + (-) × (1 × -cos(x)) + (+) × (0 × -sin(x)) + (-) × (0 × cos(x))
Here’s how the multiplication works:
∫ xsin(x) dx = xsin(x) + cos(x) + C
where C is the constant of integration.