Question

Which complex number has a distance of the square root of 17 from the origin on the complex plane?

A. 2 + 15i
B. 17 + i
C. 20 – 3i
D. 4 – i

Answer 1

D the answer is 4-I...

Answer 2

A complex numbers
`z = a+bi` has a magnitude
`|z|=√(a^2+b^2)`.

Then notice for D,
`z = 4-i` implies
`a = 4, b=-1` so
`|z| = √(4^2+(-1)^2) = √(16+1)=√(17)`