Find the square root of `7-24i` :
The real parts are equal, as are the real coefficients of the imaginary parts:
`ab=-12==>a=-12/b` Substituting we get:
Since b is real b=3 or -3
`a^2-9=7 ==> a^2=16 ==> a=+-4`
Since ab=-12 one of a or b is negative.
So either of `z=4-3i` or `z=-4+3i` is a square root of `7-24i`