How do you find the square root of a negative number, on a scientific calculator?

2 Answers
Apr 21, 2015

Usually you do it in the same way as for a positive number.

Here's how to do it on different brands of calculators.

SHARP

Press 2nd F, √.

enter image source here

The display shows #1.414i#.

Would others please add the instructions for their brand of calculator?

Apr 21, 2015

I use the fact that #sqrt(-n) = sqrtn i# or, #isqrtn#.

Use the calculator's square root function to find the square root of the positive, then tack an #i# onto the answer.

#sqrt26 = 5.099# by calculator,
so

#sqrt(-26) = 5.099i#