Loading [MathJax]/jax/output/SVG/jax.js
 
+0  
 
+1
969
2
avatar+501 

Is my solution correct?

Question:  Find all z, such that (z+1)7=z7.

 

 

My answer:  Since z0, we can divide by z7 on both sides to get (z+1z)7=1. If we let w=z+1z, then w is equal to the 7th roots of unity. We can manipulate w=z+1z by multiplying both sides by z, then subtracting z from both sides to get 1=zwz. We can then divide both sides by w1 to get z=1w1


The seven roots of unity are 1, e2iπ7, e4iπ7, e6iπ7, e6iπ7, e4iπ7, e2iπ7. z=111 if w=1 is not defined, and we can see that it doesn't work for (z+1)7=z7, either, so the solutions for z are 1e2iπ71, 1e4iπ71, 1e6iπ71, 1e6iπ71, 1e4iπ71, and 1e2iπ71, respectively.

 Sep 7, 2019
 #1
avatar+6251 
+2

looks good

 Sep 7, 2019
 #2
avatar+501 
+1

Thanks!

Davis  Sep 8, 2019

0 Online Users