ELI5: Explain Like I'm 5

Equation of a line

Imagine you have a piece of paper and you draw a line on it. This line has a start point and an end point, and it goes either up or down or left or right.

Now, imagine you have a special rule called a ruler. This ruler can tell you how long the line is and in what direction it points. It can also tell you how far the line is from the starting point.

When we talk about the equation of a line, we are using the ruler to help us describe the line in a different way. Instead of just saying where the line starts and ends, we can use a formula to tell us everything we need to know about the line.

The equation of a line is written in the form y = mx + b. In this formula, y is the vertical position of a point on the line, x is the horizontal position of that point, m is the slope of the line, and b is the y-intercept of the line.

So basically, if you know the slope of the line (how steep it is), and where it crosses the y-axis (the y-intercept), you can use the equation of the line to figure out where it will be at any given x value.

For example, if the equation of the line is y = 2x + 3, we know that the slope of the line is 2 (it goes up 2 units for every 1 unit it goes to the right), and the y-intercept is 3 (it crosses the y-axis at point (0,3)). This means that if we want to find out where the line will be when x = 4, we can plug that into the equation: y = 2(4) + 3, which gives us y = 11. So the line will be at point (4,11).

Overall, the equation of a line is just a fancy way of describing where a line starts, where it ends, and how it looks in between.