51�Թ�

a mathematical theorem that gives the expansion of any binomial raised to a positive integral power, n . It contains n + 1 terms: ( x + a ) n = xn + nx ^{n – 1} a + [ n ( n –1)/2�� xn ^– ² a ² +…+ ( nk ) xn ^– kak + … + an , where ( nk ) = n !/( ��–k )! k !, the number of combinations of k items selected from n

The theorem that specifies the expansion of any power of a binomial, that is, (a + b) ^m . According to the binomial theorem, the first term of the expansion is x ^m, the second term is mx ^{m - 1} y, and for each additional term the power of x decreases by 1 while the power of y increases by 1, until the last term y ^m is reached. The coefficient of x ^{m - r} is m![r!(m − r)!]. Thus the expansion of (a + b) ³ is a ³ + 3 a ² b + 3 ab ² + b ³.