Question

State which of the following are infinite sets.
$\left(i\right)A=\{x:x\in Z:x$ is odd$\}$
$\left(ii\right)B=\{x:x\in R:<-10\}$

• A. $\left(i\right)$ only
• B. $\left(ii\right)$ only
• C. $\left(i\right)$ and $\left(ii\right)$ both
• D. Neither $\left(i\right)$ nor $\left(ii\right)$

Answer 1

The correct option is C $\left(i\right)$ and $\left(ii\right)$ both

$\left(i\right)A=\{x:x\in Z:x^2$ is even $\}$
$A=\{...,-3,-1-1,3,...\}$ which is an infinite set.
$\left(ii\right)B=\{x:x\in R:-2<x<-4\}$
$B=\{...,-14,-13,-12,-11\}$ so it is an infinite set.