For what value of $k$ do the equations $2x^2 + kx - 5 = 0$ and $x^2 - 3x - 4 = 0$ have a common root?

If the equations $ax^2 + bx + c = 0$ and $cx^2 + bx + a = 0$ $(a \neq c)$ have a common negative root,then the value of $a - b + c$ is:

If a root of the equation $ax^2 + bx + c = 0$ is the reciprocal of a root of the equation $a'x^2 + b'x + c' = 0$,then:

If $ax^2 + bx + c = 0$ and $bx^2 + cx + a = 0$ have a common root and $a, b, c$ are non-zero real numbers,then $\frac{a^3 + b^3 + c^3}{abc} = $

The quadratic equations $x^2-6x+a=0$ and $x^2-cx+6=0$ have one root in common. If the other roots of the first and second equations are integers and are in the ratio $4:3$,then their common root is

Let $\alpha$ be a common root of the equations $x^3-2x-25\lambda=0$ and $3x^3-8x-\frac{175}{3}\lambda=0$,where $\lambda > 0$. Then $\lambda=$