Quadratic equations and inequalities

9000022901

Level: 
C
An arrow has been shot at the angle \(60^{\circ }\) at the speed \(10\, \mathrm{m}\, \mathrm{s}^{-1}\). Find the time when the height equals to the horizontal distance from the take-off point. Hint: The position is given by the equations \(x = v_{0}t\cdot \cos \alpha \), \(y = v_{0}t\cdot \sin \alpha -\frac{1} {2}gt^{2}\). Use \(g = 10\, \mathrm{m}\, \mathrm{s}^{-2}\) as an acceleration of gravity.
\(\left (\sqrt{3} - 1\right )\, \mathrm{s}\)
\(\left (\sqrt{3} + 1\right )\, \mathrm{s}\)
\(\sqrt{3}\, \mathrm{s}\)
\(\left (\sqrt{2} - 1\right )\, \mathrm{s}\)
\(\left (\sqrt{2} + 1\right )\, \mathrm{s}\)

9000020408

Level: 
A
Which of the given equations have at least one root the same? \[ \begin{aligned} x^{2} + 8x + 15 & = 0 &\text{(1)} \\x^{2} - 8x + 15 & = 0 &\text{(2)} \\x^{2} +\phantom{ 8}x - 12 & = 0 &\text{(3)} \\x^{2} - 2x -\phantom{ 1}8 & = 0 &\text{(4)} \\\end{aligned}\]
equations (2) and (3)
equations (1) and (3)
equations (2) and (4)
Such a pair does not exist.