Question

Write the set of values of $a$ for which the equation $x^2+ax-2=0$ has real roots.

Answer 1

$x^2+ax-2=0$

If equation has real roots $△\ge 0$

$discriminant=b^2-4ac\ge 0$

$a^2-4(-2)\left(1\right)\ge 0$

$a^2\ge -8$

$\therefore$ It has real roots for all values of $a$.