In rule method the null set is represented by
$\{\}$
$\phi $
$\{ x:x = x\} $
$\{ x:x \ne x\} $
What universal set $(s)$ would you propose for each of the following :
The set of isosceles triangles
List all the subsets of the set $\{-1,0,1\}.$
Examine whether the following statements are true or false :
$\{ a,e\} \subset \{ x:x$ is a vowelin the English alphabet $\} $
Write the solution set of the equation ${x^2} + x - 2 = 0$ in roster form.
Write the set $\{ x:x$ is a positive integer and ${x^2} < 40\} $ in the roster form.