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Conjugate

Conjugate

One-page printable reference

See It in Action

Two examples of the idea done right—and one common look-alike that is not right.

EXAMPLE

EXAMPLE

NON-EXAMPLE

Definition

In Algebra 1, the term "conjugate" typically refers to a pair of binomials involving square roots. When you have an expression like a + sqrt(b), its conjugate is a - sqrt(b), and vice versa.


For example:

  • The conjugate of 3 + sqrt(5) is 3 - sqrt(5).

  • The conjugate of 2 - sqrt(7) is 2 + sqrt(7).


Conjugates are often used to simplify expressions, especially when multiplying binomials with square roots. When you multiply a binomial by its conjugate, the result is a difference of squares, which eliminates the square root.


For example:

An equation. Open parentheses three plus square root of 5 close parentheses times open parentheses three minus square root of five close parentheses equals three squared minus square root of five squared equals nine minus five equals 4.

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This term is one piece. Our courses build it into everything around it—short videos, practice, and the “why” behind every concept.

Algebra 1

Lines, slope, functions & more

Geometry

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