Step 1: Find the slope
Pick any two points on the line and use the slope formula to solve for the slope.
Slope Formula: (y2 - y1) / (x2 - x1)
Point 1 = (1,2)
Point 2 = (0,-1)
Slope = (-1 - 2) / (0 - 1) = -3 / -1 = 3
Step 2: Find the y-intercept
A graph may show the y-intercept, or where the line crosses the y-axis. But, if it was not shown, we can find it by plugging in a point and the y-intercept into slope-intercept form.
Slope-Intercept Form: y = mx + b
Point = (1,2)
Slope = 3
2 = 3(1) + b
2 = 3 + b
b = -1
Step 3: Put everything into slope-intercept form
Now that we know the slope and the y-intercept, all that's left to do is plug it into slope-intercept form.
Slope-Intercept Form: y = mx + b
Slope = 3
Y-Intercept = -1
ANSWER: y = 3x - 1
Hope this helps!
