## What is an affine function?

An affine function, also known as first degree polynomial function, is a function of f : ℝ→ℝ, defined as the form **y=ax+b** or **f(x) = ax + b**, where **a** and **b** are real numbers and **a ≠ 0, b ≠ 0**.

In this type of functions the **a** is called the coefficient of x and represents the growth rate, variation rate or angular coefficient. The **b** is called the constant term and represents the y-interception.

## How to plot the graph of y = x + 3?

To plot the graph, one needs to know at least two points. The graph of an affine function is a **straight line **that intercepts the **y-axis** in the point **(0, b)**.

It is necessary to calculate the root (or zero) of the function. The root, or zero, is where the function intercepts the **x-axis**, and can be calculated equalizing **y=0**.

x + 3 = 0 -> x = -3

The two points to plot the graph will be:

And the graph will look something like: