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Change of the sign of a square root
This article is about conjugation by changing the sign of a square root. For other uses, see Conjugate (disambiguation).
In mathematics, the conjugate of an expression of the form is provided that does not appear in a and b. One says also that the two expressions are conjugate.
As
and
the sum and the product of conjugate expressions do not involve the square root anymore.
This property is used for removing a square root from a denominator, by multiplying the numerator and the denominator of a fraction by the conjugate of the denominator (see Rationalisation). An example of this usage is:
Hence: