If the roots of the equation ax² + bx + c = 0 are equal then c = ?

If α and β are the roots of the equation 3x² + 8x + 2 = 0 then = ?

The roots of the equation ax² + bx + c = 0 will be reciprocal of each other if

If the equation 9x² + 6kx + 4 = 0 has equal roots then k = ?

If the equation x² + 2(k + 2)x + 9k = 0 has equal roots then k = ?