The roots of the equation px² + qx + r = 0, where p ≠ 0, are given by:

1. $x = \dfrac{-p \pm \sqrt{q^{2} - 4pr}}{2p}$

2. $x = \dfrac{-q \pm \sqrt{q^{2} - 2pr}}{4p}$

3. $x = \dfrac{-q \pm \sqrt{q^{2} - 4pr}}{2p}$

4. $x = \dfrac{-q \pm \sqrt{q^{2} - 4pr}}{2q}$

The discriminant of the quadratic equation ax² + bx + c = 0, a ≠ 0 is given by:

1. b² - 2ac

2. b² - ac

3. b² - 4ac

4. none of these

If the roots of the quadratic equation, ax² + bx + c = 0, a ≠ 0 are real and equal, then each root is equal to:

1. $\dfrac{-a}{2b}$

2. $\dfrac{-b}{2a}$

3. $\dfrac{-2a}{b}$

4. $\dfrac{-c}{2a}$

If the discriminant of the quadratic equation, ax² + bx + c = 0, a ≠ 0 is greater than zero and a perfect square and a, b, c are rational, then the roots are:

1. rational and equal

2. irrational and unequal

3. irrational and equal

4. rational and unequal