Sentence 43: \(U\left( {21} \right) \) is;

A. \(U\left( {21} \right) = \left\{ {1;7;21} \right\}\)

B. \(U\left( {21} \right) = \left\{ {1;3;7;21} \right\}\)

C. \(U\left( {21} \right) = \left\{ {1;3;;6;7;21} \right\}\)

D. \(U\left( {21} \right) = \left\{ {1;3;7} \right\}\)

Notice that 21 is divisible by 1, 3, 7, and 21, so:

\(U\left( {21} \right) = \left\{ {1;3;7;21} \right\}\)

===============

Reader Interactions