Question

Find the least positive value for $k$ for which the equation $x^2+kx+4=0$ has real roots.

Answer 1

$x^2+kx+4=0$

For positive root least value of $k$ is $\sqrt{b^2-4ac}\ge 0$ where equation is ax^2+bx+c$

Here, $k^2-16\ge 0$

$⟹k\ge 4$ or $k\le -4$

Hence $-4\le k\ge 4$