What is the sqrt(-25)25?

1 Answer
Aug 14, 2016

sqrt(-25) = 5i25=5i

Explanation:

-2525 has two square roots 5i5i and -5i5i, but the expression sqrt(-25)25 denotes the principal square root, which by convention is 5i5i.

In general, if x < 0x<0 then sqrt(x) = (sqrt(-x))ix=(x)i. Hence in our example:

sqrt(-25) = (sqrt(25))i = (sqrt(5^2))i = 5i25=(25)i=(52)i=5i