Riemann Sums Math Example 3

Follow the full solution, then compare it with the other examples linked below.

Example 3

easy
Use a midpoint sum with n=2n=2 to approximate โˆซ04(x+1)โ€‰dx\int_0^4 (x+1)\,dx.

Solution

  1. 1
    ฮ”x=2\Delta x = 2. Midpoints: x=1,3x = 1, 3.
  2. 2
    M2=2(f(1)+f(3))=2(2+4)=12M_2 = 2(f(1)+f(3)) = 2(2+4) = 12.

Answer

M2=12M_2 = 12
For a linear function, the midpoint rule is exact regardless of nn. The exact integral is also 12.

About Riemann Sums

A method of approximating the definite integral โˆซabf(x)โ€‰dx\int_a^b f(x)\,dx by dividing the interval [a,b][a, b] into subintervals and summing the areas of rectangles (or trapezoids) whose heights are determined by the function.

Learn more about Riemann Sums โ†’

More Riemann Sums Examples