What is the definite integral of zero?

1 Answer

If you mean int_a^b0dxba0dx, it is equal to zero.

This can be seen in a number of ways.

  • Intuitively, the area under the graph of the null function is always zero, no matter over what interval we chose to evaluate it. Therefore, int_a^b 0 dxba0dx should be equal to 00, although this isn't an actual computation.

  • Note the derivative of a constant function d/(dx)C=0ddxC=0.
    By the Fundamental Theorem of Calculus, we get
    int_a^b 0 dx = int_a^b d/(dx) C dx = C(b) - C(a) = C - C = 0ba0dx=baddxCdx=C(b)C(a)=CC=0

  • Consider the Riemann Sums of the function 00:
    sum_i^n f(x_i) Delta x_i = sum_i^n 0 Delta x_i ,
    where Delta x_i are the lengths of the divisions of the interval [a,b].
    No matter how we choose to divide the interval, this sum is always equal to 0, since 0 Delta x_i=0.
    Therefore, the limit
    lim_(n to oo) sum_i^n 0 Delta x_i = int_a^b 0 dx = 0