If the difference between the roots of the equation $${x^2} + kx + 1 = 0$$ is strictly less than $$\sqrt 5 $$, where $$\left| k \right| \ge 2$$, then k can be any element of the interval

If the graph of a quadratic polynomial lies entirely above X-axis, then which one of the following is correct?

If cot $$\alpha$$ and cot $$\beta$$ are the roots of the equation x² + bx + c = 0 with b $$\ne$$ 0, then the value of cot ($$\alpha$$ + $$\beta$$) is

The sum of the roots of the equation x² + bx + c = 0 (where, b and c are non-zero) is equal to the sum of the reciprocals of their squares. Then, $${1 \over c},b,{c \over b}$$ are in