### What is Y-Intercept?

In this article, we will define and discuss the formula of how to calculate y-intercept. The 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 1:**

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**

Hence, **y = 3x – 1**

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

**Example 2:**

Suppose you have a straight line whose gradient is 0.8 and one of the point on the line is (4,2).

Since **y – a = m ( x – b )**

Therefore;

**y – 4 = 0.8( x – 2**)

**y – 4 = 0.8x – 1.6**

Therefore, **y = 0.8x – 5.6**

From the formula y = mx + b, from the answer above, the value of the y-intercept is -5.6