Y Intercept is the point where a line or curve crosses the y-axis of a graph or in other words where x=0.

Knowledge of the y intercept can be used when graphing lines or when writing an equation in slope-intercept form.

**Formula to calculate y-intercept.**

We get the y-intercept by using the equation of a straight line which is;

**y = mx + b**

Where;

- m is the gradient of the slope
- b is the y-intercept.

We can use the following formula to calculate the y-intercept.

**y – a = m ( x – b )**

a and b being a point on a line.

**Example:**

Suppose you have a straight line whose gradient is 3 and a point 2,1, calculate its y-intercept.

Since the y-intercept is when x=0, therefore;

**y – 2 = 3 ( x – 1 )**

**y – 2 = 3x – 1**

**y = 3x – 1**

Therefore, the number that has replaced b is -1, which means that -1 is the y-intercept.