If one root of a quadratic equation $ax^2 + bx + c = 0$ is $\frac{-b + \sqrt{D}}{2a}$,then the other root is $\ldots \ldots \ldots \ldots$.

In the centre of a rectangular lawn of dimensions $50\, m \times 40\, m$,a rectangular pond has to be constructed so that the area of the grass surrounding the pond would be $1184\, m^{2}$ [see $Fig.$]. Find the length and breadth of the pond. (in $m$)

The length of a rectangle is $2\,cm$ less than $3$ times its breadth. If its area is $280\,cm^2$,then find its length.

Solve the following equation using the quadratic formula,if the equation has a solution in $R$: $5x^{2} - 3x - 2 = 0$.

Find the roots of the following quadratic equation by the method of completing the square: $3x^2 + 11x + 10 = 0$.

If the value of the discriminant of a quadratic equation is $D = 0$,then the value of each root is .... .