The roots of the quadratic equation px² - qx + r = 0 are real and equal if :

(a) p² = 4qr

(b) q² = 4pr

(c) –q² = 4pr

(d) p² > 4qr

If matrix 𝐴 = $\begin{bmatrix$}[r] 2 & 2 \ 0 & 2 \end{bmatrix}\text{ and } A^2 = \begin{bmatrix}[r] 4 & x \ 0 & 4 \end{bmatrix}, then the value of x is :

1. 2

2. 4

3. 8

4. 10

Points A(x, y), B(3, -2) and C(4, -5) are collinear. The value of y in terms of x is ∶

1. 3x - 11

2. 11 - 3x

3. 3x - 7

4. 7 - 3x

The given table shows the distance covered and the time taken by a train moving at a uniform speed along a straight track.

The values of x and y are :

1. x = 4, y = 150

2. x = 3, y = 100

3. x = 4, y = 100

4. x = 3, y = 150