Worlds of David Darling
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In mathematics:
  1. A number used to build up another number by repeated multiplication; in other words, one of the equal factors of a given number. For example, since 2 × 2 × 2 = 8, two is said to be the third root or cube root of eight. Of particular interest is i, the square root of -1. (See also exponent; power.)

  2. A solution of an equation; i.e. the value(s) of the variable for which the equation holds. For example, 3 is a root of the equation x2 = 9. A root is also called a zero of a function because it is a value that will make the function zero (x = 3 will make the function f(x) = x2 - 9 zero).
The word comes from the Indo-European werad, which originally meant the roots of a plant but was later generalized to mean the origins or beginnings of something, whether it was physical or mental.

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