Question

How do you find `abs( -4-9i )`?

Answer 1

`|-4-9i|~=9.85.`

Explanation:

For a complex no. `z=x+iy,` `|z|=|x+iy|=sqrt(x^2+y^2).`

Hence, `|-4-9i|=sqrt(16+81)=sqrt97~=9.85.`