The number of distinct real roots of the equation $x ^{7}-7 x -2=0$ is
$5$
$7$
$1$
$3$
If $a, b, c, d$ are four distinct numbers chosen from the set $\{1,2,3, \ldots, 9\}$, then the minimum value of $\frac{a}{b}+\frac{c}{d}$ is
The sum of all real values of $x$ satisfying the equation ${\left( {{x^2} - 5x + 5} \right)^{{x^2} + 4x - 60}} = 1$ is ;
If $x,\;y,\;z$ are real and distinct, then $u = {x^2} + 4{y^2} + 9{z^2} - 6yz - 3zx - zxy$ is always
The roots of the equation ${x^4} - 2{x^3} + x = 380$ are
The solution set of the equation $pq{x^2} - {(p + q)^2}x + {(p + q)^2} = 0$ is