Binomial theorem is a part of algebra that describes the expansion of expressions in the form of (a+b)ⁿ, where a and b are numbers and n is an integer. The general expansion is written as

(a + b)^n = Σ (from r = 0 to n) [nCr * a^(n-r) * b^r]

Here, Σ represents summation, nCr is the binomial coefficient. The value of r ranges from 0 to n.