Question

Help on complex numbers

1) what is the reciprocal of 6i
2) what is the additive inverse of -4+5i
3) find the multiplicative inverse of 2+i
4) find the reciprocal of -3+5i
5) find the magnitude of 5-12i

Answer 1

1) 1/6i=-6i
2) - (-4+5i)=4-5i
3) 1/(2+i)=(2-i)/(4+1) = (2-i)/5
4)1/(-3+5i)=(-3-5i)/(9+25)
5) square root of ( 5*5 + 12*12) = 13