Let\(S = \left\{z∈C : z^2+\overline{z} = 0 \right\}\). Then \(∑_{z∈S}(Re(z)+Im(z))\)is equal to____.
If the system of equations $ x + y + z = 6 $, $ 2x + 5y + \alpha z = \beta $, $ x + 2y + 3z = 14 $ has infinitely many solutions, then $ \alpha + \beta $ is equal to:
Let a vertical tower AB of height 2h stands on a horizontal ground. Let from a point P on the ground a man can see up to height h of the tower with an angle of elevation 2α.When from P, he moves a distance d in the direction of \(\overrightarrow{AP}\).he can see the top B of the tower with an angle of elevation α. if \(d = \sqrt7\) h, then tan α is equal to