Write the set $\left\{\frac{1}{2}, \frac{2}{3}, \frac{3}{4}, \frac{4}{5}, \frac{5}{6}, \frac{6}{7}\right\}$ in the set-builder form.
We see that each member in the given set has the numerator one less than the denominator. Also, the numerator begin from $1$ and do not exceed $6 .$ Hence, in the set-builder form the given set is
$\left\{ {x:x = \frac{n}{{n + 1}},} \right.$ where $n$ is a natural number and $\left. {1 \le n \le 6} \right\}$
Make correct statements by filling in the symbols $\subset$ or $ \not\subset $ in the blank spaces:
$\{ x:x$ is an equilateral triangle in a plane $\} \ldots \{ x:x$ is a triangle in the same plane $\} $
Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?
$1 \in A$
Which of the following are sets ? Justify your answer.
The collection of all natural numbers less than $100 .$
Write the following intervals in set-builder form :
$\left( { - 3,0} \right)$
The number of elements in the set $\{ (a,\,b):2{a^2} + 3{b^2} = 35,\;a,\,b \in Z\} $, where $Z$ is the set of all integers, is