If $a, b, c, d$ and $p$ are distinct real numbers such that $(a^2 + b^2 + c^2)\,p^2 -2p\, (ab + bc + cd) + (b^2 + c^2 + d^2) \le 0$, then
$a, b, c, d$ are in $A.P.$
$ab =cd$
$ac = bd$
$a, b, c, d$ are in $G.P.$
If the expression $\left( {mx - 1 + \frac{1}{x}} \right)$ is always non-negative, then the minimum value of m must be
The number of ordered pairs $(x, y)$ of positive integers satisfying $2^x+3^y=5^{x y}$ is
The equation $\sqrt {3 {x^2} + x + 5} = x - 3$ , where $x$ is real, has
If $\sqrt {3{x^2} - 7x - 30} + \sqrt {2{x^2} - 7x - 5} = x + 5$,then $x$ is equal to
The number of real solutions of the equation $|x{|^2}$-$3|x| + 2 = 0$ are