Question

((2-i)^2) / (1+2i) also "i" is the imaginary unit, not a variable. How do you calculate this? the answer is -1-2i

Answer 1

Well you treat i like a variable pretty much unless you get an i^2, because that equals -1 (since i=sqrt(-1)..). Multiply the numerator out. You can't divide imaginary numbers, you have to multiply by the "complex conjugate", so you multiply the numerator and denominator both by (1-2i).