The roots of the quadratic equation $\ldots \ldots \ldots \ldots$ are $-4$ and $5$.

The speed of a motorboat in still water is $25 \text{ km/hr}$. In a river, it covers $60 \text{ km}$ downstream and the same distance upstream in a total time of $5 \text{ hours}$. Find the speed of the current of the river. (The speed of the current of the river is less than the speed of the motorboat in still water.) (in $\text{ km/hr}$)

Find the discriminant of the following quadratic equation and hence determine the nature of the roots of the equation: $4x^{2} + 11x + 10 = 0$

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.

$x = \dots$ is a solution of the quadratic equation $x^{2} + 7x + 12 = 0$.

Solve the following equation using the method of factorization and write its solution set: $\frac{x+1}{x-1} + \frac{x-2}{x+2} = 3$