Math Is Fun Forum

BLANK

Guest

Help, please!

Prove that if w,z are complex numbers such that |w|=|z|=1 and wz!= -1, then (w+z)/(1+wz) is a real number.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

Re: Help, please!

hi BLANK,

Welcome to the forum.

I think this has been asked before and fairly recently but I haven't managed to find it yet.  You have typed

wz!= -1

which seems like a typo.  ! would be 'factorial' and that makes no sense in this context.  If we drop the ! then wz = -1 and that also makes no sense as it makes the denominator of the expression zero.

Please respond with a clarification.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

Re: Help, please!

Found it:

http://www.mathisfunforum.com/viewtopic.php?id=23495

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

dogleg

Member

Registered: 2018-04-20

Posts: 1

Re: Help, please!

Hi. I am new to this forum and very rusty in my math. I am trying to relearn roots of expressions like     : Square root of  x-3 =     , and fourth root of x-3   for example.  Help me get started please.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

Re: Help, please!

hi dogleg,

Did you mean

Have a look here:

http://www.mathsisfun.com/exponent.html

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob