what is Binomial Theorem? pls. explain

Binomial expression:  An algebraic expression consisting of two terms with a positive or negative sign between them is called a binomial expression.

 Example: (a+b)

 Binomial Theorem: When a binomial expression is raised to a power ‘n’ we would like to be able to expand it. The binomial theorem assists us in doing this. It converts such an expression into a series.

 Binomial Theorem for positive integral index:

 (x+y)ⁿ = xⁿ  +  ⁿC₁x^n-1y + ⁿC₂x^n-2y² + - - - -- + ⁿC_rx^n-ry^r +  - - - - -- - + - - - - -- -- - + ⁿC_n-1xy^n-1   + ⁿC_nyⁿ.

where ⁿC_r = n!/(n-r)!r!

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TopperLearning.