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Theorem

Binomial Theorem

Algebra

The binomial theorem is a result in algebra that gives a formula for expanding a power of a two term expression such as x plus y raised to the n. It states that when this expression is expanded, each term takes the form of a coefficient multiplied by x raised to one exponent and y raised to another, where the two exponents always add up to n. For example, x plus y raised to the fourth power expands to x to the fourth, plus four x cubed y, plus six x squared y squared, plus four x y cubed, plus y to the fourth. The coefficient of each term, known as a binomial coefficient, depends only on n and the exponent of x, and the theorem gives a systematic way to compute every one of these coefficients without multiplying the expression out term by term.

Facts
Statement
For a positive integer n, the binomial theorem gives the expansion of the two term sum x plus y raised to the n as the sum, for k running from 0 to n, of the binomial coefficient n choose k times x raised to the power n minus k times y raised to the power k. 1
Proof Year
1654 1
Classification
Statement Form
Identity or Equation 1
Sources
1. Binomial Theorem (Wikipedia)
Wikimedia Foundation
  • lead paragraph, statement of the theorem
    In elementary algebra, the binomial theorem (or binomial expansion) describes the algebraic expansion of powers of a binomial.
  • History section, rigorous proof by induction
    The second formula was rigorously proven by Pascal in 1654 through the use of complete induction.
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