In mathematics you will often have to deal with lines, in algebra and geometry. If you know how to find the slope of a line, you can deduce many things: for example, if two lines are parallel or perpendicular to each other, where they intersect and other concepts. Finding the slope of a straight line is quite simple. Keep reading this article to learn how.
Steps
Method 1 of 2: Slope formula
Step 1. Learn the slope formula
The slope is defined as "rise over run".
Method 2 of 2: Solve by slope
Step 1. Choose a line to calculate the slope of
It must be a straight line. The slope of a non-straight line cannot be found.
Step 2. Take any two coordinates of two points on the line
The coordinates are the x and y points, denoted by (x, y). It doesn't matter which points you choose, they must be two points on the same line.
Step 3. Choose which coordinates are dominant in the equation
It doesn't matter which ones you choose: the important thing is that they remain the same throughout the calculation. The dominant coordinates will be x 1 and y 1. The other coordinates will be x 2 and y 2.
Step 4. Write the equation using the y coordinates at the top and the xs at the bottom
Step 5. Find the difference between the two ys
Step 6. Find the difference between the two xs
Step 7. Divide the result by the y by the result of the x
Simplify the number if possible.
Step 8. Check to see if the result is plausible
- Upward sloping lines always have positive numbers, even when it comes to fractions.
- Downward sloping lines always have negative numbers, even when it comes to fractions.
Example
- They are given: An AB line.
- Coordinates: A - (3, 4) B - (6, 8)
- y2-y1): 2-1 = 1; Increment = 1
- x2-x1): 2-0 = 2; Stroke = 2
- AB Line Slope = (Increment / Stroke) = 1/2.
Advice
- Once you have established the dominant coordinates, do not change them, otherwise you will have the wrong result.
- You found m of the straight line formula: y = mx + b, where y is the y coordinate of any point, m is the slope, x is the x coordinate corresponding to the y of a given point, and b is the y intercept.
- Also consult the textbook or ask your teacher for help.
