Question

Write the following sets in roster form:
$\{x|x=n^2-1,n\in Nandn<5\}$

Answer 1

The given set can be written as
Natural number less than $5$ are $1,2,3,4$
i.e., $n=1,2,3,4$
Given $x=n^2-1,$ putting $n=1,2,3,4,$ we get
$x=1^2-1,2^2-1,3^2-1,4^2-1=0,3,8,15$
The given set can be written as $\{0,3,8,15\}$(roster form)