Editing Nth root (section)

===Square roots===
{{Main article|Square root}}
[[Image:Square-root function.svg|thumb|right|The graph <math>y=\pm \sqrt{x}</math>.]]
A '''square root''' of a number ''x'' is a number ''r'' which, when [[square (algebra)|squared]], becomes ''x'':

<math display="block">r^2 = x.</math>

Every positive real number has two square roots, one positive and one negative.  For example, the two square roots of 25 are 5 and −5.  The positive square root is also known as the '''principal square root''', and is denoted with a radical sign:

<math display="block">\sqrt{25} = 5.</math>

Since the square of every real number is nonnegative, negative numbers do not have real square roots. However, for every negative real number there are two [[imaginary number|imaginary]] square roots.  For example, the square roots of −25 are 5''i'' and −5''i'', where ''[[imaginary unit|i]]'' represents a number whose square is {{math|−1}}.