Question

Let $P$ be the set of $42^{\text{nd}}$ roots of unity, and let $Q$ be the set of $70^{\text{th}}$ roots of unity. How many elements do $P$ and $Q$ have in common

Answer 1

The answer to the given question can be defined as follows:

Explanation:

`\to GCF(42, 70) = 7`

Therefore, the common roots of unity were

`\to e^{\pm i 2\pi (k)/(7)}\\\\\ where \\ \\ k=0,1,...... 6`

That's why the answer is 14 for these