Which of the following is not a quadratic equation?

1. (x + 2)² = 2(x + 3)
2. x² + 3x = (-1)(1 - 3x)
3. (x + 2)(x - 1) = x² - 2x - 3
4. x³ - x² + 2x + 1 = (x + 1)³

If $\dfrac{1}{2}$ is a root of the quadratic equation 4x² - 4kx + k + 5 = 0 , then the value of k is

1. -6
2. -3
3. 3
4. 6

If one root of a quadratic equation with rational coefficients is $\dfrac{3 - \sqrt{5}}{2}$, then the other root is

1. $\dfrac{-3 - \sqrt{5}}{2}$

2. $\dfrac{-3 + \sqrt{5}}{2}$

3. $\dfrac{3 + \sqrt{5}}{2}$

4. $\dfrac{\sqrt{3} + 5}{2}$

If the equation 2x² - 5x + (k + 3) = 0 has equal roots then the value of k is

1. $\dfrac{9}{8}$

2. $-\dfrac{9}{8}$

3. $\dfrac{1}{8}$

4. $-\dfrac{1}{8}$