The general equation of a straight line is:

where m is the gradient and c is the y-intercept (where the straight line cuts the y-axis)

Find the gradient and y-intercept for the straight line with equation ?

so y-intercept is (0, 7)

Try these example questions

- Question
Find the gradient and y-intercept for the straight line with equation

so y-intercept is (0, 3).

- Question
Find the gradient and y-intercept for the straight line with equation

so y-intercept is (0, -4).

- Question
Find the equation of the straight line shown below.

To find the equation of a straight line we need to know the gradient and the y-intercept.

Looking at the graph, the straight line cuts the y-axis at (0, 3) therefore c = 3.

Remember that the formula to calculate the gradient is:

Therefore

Since the straight line shown above is a downward slope, then:

So, the equation of the straight line is:

- Question
Find the equation of the straight line shown below.

y-intercept is (-3, 0) therefore c = -3

Therefore, the equation of the straight line is:

- Question
Which of these lines in the above diagram are horizontal and which are vertical?

Horizontal lines: and .

Vertical lines: and .