# LeftSum Command

From GeoGebra Manual

- LeftSum[ <Function>, <Start x-Value>, <End x-Value>, <Number of Rectangles> ]
- Calculates the left sum of the function in the interval using
*n*rectangles. **Example:**`LeftSum[x^2 + 1, 0, 2, 4]`

yields*a*= 3.75

**Notes:**

- This command draws the rectangles of the left sum as well.
- See also the commands: RectangleSum, TrapezoidalSum, LowerSum and UpperSum