1. What is the gradient of vertical and horizontal lines?

The gradient of a horizontal line is 0.

The gradient of a vertical line is undefined.

It cannot be calculated because the x-step is 0, and division by 0 is not possible.

2. How can you tell whether a function has a straight line graph?

In the formula for the function,, the x variable and the y variable are both to the power of and all terms are being added and/or subtracted. e.g 3x + 4y = 3

3. What does it mean if there is no constant term in a linear function e.g. y = 3x?

The straight line graph of the function passes through the origin (0, 0).