Another one! I'm really sorry. This time I'm not sure where I went wrong.
Express in polar form, (1/(sqrt(21) - sqrt(7)i)*)
Conjugate, so I got (1/(sqrt(21) + sqrt(7)i))
Let z = sqrt(21) + sqrt(7)i
In modulus argument form ie. cis form, I got sqrt(30)cis(pi/6)
For the modulus of (1/(sqrt(21) - sqrt(7)i)*),
I got 1/sqrt(30)
But the answer is (sqrt(7)/14)!
Thank you very much for your time,
J.