Graphing Lines & Slope-Intercept Form

The coordinate plane has a horizontal x-axis and a vertical y-axis. A point is written (x, y): go x to the right or left, then y up or down. The middle, where they cross, is the origin (0, 0).

Slope

Slope measures how steep a line is. It is rise over run, meaning change in y divided by change in x. A positive slope goes up to the right, a negative slope goes down to the right. Slope of 2 means up 2, over 1.

Slope-intercept form: y = mx + b

• ●m is the slope (steepness and direction)
• ●b is the y-intercept, where the line crosses the y-axis
• ●Example: in y = 3x + 2, slope is 3 and the line crosses the y-axis at (0, 2)

1. 1Graph y = 2x - 1
2. 2Start at the y-intercept b = -1, so plot the point (0, -1)
3. 3Use slope m = 2 (up 2, right 1) to get the next point (1, 1)
4. 4Draw a straight line through both points