Binomial Expansion Calculator

Expand binomial expressions using the Binomial Theorem with step-by-step solutions

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Enter the terms and exponent to expand ( + )

Expanded Form of ( + )

terms using binomial coefficients

Term-by-Term Breakdown

Binomial Coefficients

These are the coefficients from row of Pascal's Triangle

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About Binomial Expansion Calculator

What is Binomial Expansion?

Binomial expansion is a method for expressing the power of a binomial (a two-term expression) as a sum of terms using the Binomial Theorem. It allows you to expand expressions like (a + b)^n into a polynomial without performing repeated multiplication.

The Binomial Theorem Formula

The Binomial Theorem states that for any non-negative integer n:

(a + b)^n = Σ C(n,k) × a^(n-k) × b^k for k = 0 to n

Where C(n,k) is the binomial coefficient, also written as "n choose k":

C(n,k) = n! / (k! × (n-k)!)

How to Use This Calculator

  1. Enter First Term (a): Input the coefficient or variable for the first term
  2. Enter Second Term (b): Input the coefficient or variable for the second term
  3. Enter Exponent (n): Input the power to raise the binomial to
  4. View Results: See the expanded form with all terms and coefficients

Pascal's Triangle and Binomial Coefficients

Pascal's Triangle provides a quick way to find binomial coefficients:

Row Coefficients
n=0 1
n=1 1, 1
n=2 1, 2, 1
n=3 1, 3, 3, 1
n=4 1, 4, 6, 4, 1
n=5 1, 5, 10, 10, 5, 1

Common Binomial Expansions

  • (a + b)² = a² + 2ab + b²
  • (a + b)³ = a³ + 3a²b + 3ab² + b³
  • (a - b)² = a² - 2ab + b²
  • (a - b)³ = a³ - 3a²b + 3ab² - b³

Frequently Asked Questions

What is the binomial coefficient?

The binomial coefficient C(n,k) tells you how many ways you can choose k items from n items. It's also the coefficient of the kth term in the binomial expansion.

Can I expand negative exponents?

The simple binomial theorem applies to non-negative integer exponents. For negative or fractional exponents, you need the generalized binomial theorem which produces infinite series.

What's the difference between (a+b)^n and (a-b)^n?

When expanding (a-b)^n, the signs alternate: positive for even powers of b, negative for odd powers of b.

How many terms are in a binomial expansion?

The expansion of (a+b)^n always has exactly (n+1) terms.

Note: This calculator handles non-negative integer exponents. For other cases, consult a more advanced tool.