APPENDIX A.3 - Complex Numbers

Section A.3, page A-16

Problem 10

We want to know where |z+1| is greater than or equal to |z|. This corresponds to the real inequality: x^2+y^2 <= (x+1)^2+y^2  Let's see:

>   simplify((x+1)^2+y^2-(x^2+y^2));

2*x+1

So we need 2x+1 bigger than 0. So the region where this is true is to the right of the vertical line Re(z)=-1/2.

Problem 24

To find square roots of i, we solve the equation:

>   solve(z^2=I);

1/2*2^(1/2)+1/2*I*2^(1/2), -1/2*2^(1/2)-1/2*I*2^(1/2)