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About

Factorizing is useful for finding roots, but expansion is essential for simplification and solving linear differential equations. This tool focuses on the "Expansion" phase of algebra, specifically applying the Distributive Law to remove parentheses. It is particularly useful when checking manual work on complex nested expressions where keeping track of negative signs is difficult.

The calculator employs the FOIL method (First, Outer, Inner, Last) logic for binomials but generalizes this to any polynomial multiplication. It breaks down the process term-by-term, ensuring that every element in the first polynomial multiplies every element in the second. This prevents the common "Freshman's Dream" error where students incorrectly assume x+y2 equals x2+y2.

algebra expansion FOIL brackets math

Formulas

The General Distributive Law for any number of terms is:

mi=1 ai × nj=1 bj = mi=1 nj=1 (aibj)

When expanding (x + a)n, the coefficients are determined by the combination formula:

nk = n!k!(nk)!

Reference Data

Identity NameFormulaUse Case
Square of Sum(a+b)2 = a2 + 2ab + b2Parabolic expansion
Square of Diff(ab)2 = a2 2ab + b2Parabolic expansion
Diff of Squares(a+b)(ab) = a2 b2Rationalizing denominators
Cube of Sum(a+b)3 = a3 + 3a2b + 3ab2 + b3Volume expansion
Sum of Cubesa3+b3 = (a+b)(a2ab+b2)Factoring cubic roots
FOIL Rule(a+b)(c+d) = ac + ad + bc + bdGeneral binomials
Pascal Row 41, 4, 6, 4, 1Coefficients for power 4
Pascal Row 51, 5, 10, 10, 5, 1Coefficients for power 5

Frequently Asked Questions

Yes. The tool generalizes the FOIL method. If you input a trinomial multiplied by a binomial, it performs 3 × 2 = 6 individual multiplications before collecting like terms.
Yes. While the primary interface is for two distinct expressions, you can enter (x+1) into both fields to square it, or perform sequential multiplications for higher powers.
This usually happens when expanding terms with negative coefficients. The tool strictly follows sign rules: negative times negative is positive, and negative times positive is negative.