How to Solve for Slope in Algebra 1

The slope of a graphed line is the line's ratio of vertical rise to horizontal run.
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In Algebra 1, slope refers a line's ratio of vertical rise to horizontal run. In other words, slope measures the steepness or incline of a line. Slope is used in graphing functions. In formulas, slope is "m." The domain of a line is represented by "x" and the range of a line is "y." It is important to know how to find the slope of a line because understanding slope is the foundation of later Algebra 1 lessons, such as slope-intercept form, standard slope form and point-slope form.

    Know the meaning of basic terms. Positive slope refers to a line that goes up from left to right on a graph. Negative slope refers to a line that goes down as you move left to right.

    Understand and memorize the definition, or formula, of slope. When given two points with coordinates, the formula for the slope of the line containing those two points is m = (y2 - y1) / (x2 - x1). The first given coordinate is (x1,y1) and the second given coordinate is (x2, y2).

    Evaluate the two given points and plug them into the slope formula. For example, if the given coordinates are K (2, 6) and N (4, 5), the formula will look like m = (5 - 6) / (4 - 2).

    Simply and calculate values in parenthesis. For example, (5 - 6) = -1 and (4 - 2) = 2.

    Plug the new values back into the slope formula. This value is the slope. For the example, it's -1/2. Therefore, the slope of the line equals -1/2 or 0.5.

    Evaluate the value of the line's slope and determine whether the line has a negative or positive slope. For example, a line with a slope of -1/2 has a negative slope. Thus, you can visualize the line on a graph moving down as it moves left to right.

    Practice solving for slope with other examples until you have fully grasped the concept of slope and its formula.


    • The slope of a horizontal line is 0. The slope of a vertical line is undefined.


About the Author

Based in the Philadelphia area, Rachel Costello has been a freelance writer since 2008. Her areas of expertise include philosophy, literature, education, food and wine. Costello has worked for several marketing companies and her articles have been hosted by many blogs and websites. She received her Bachelor of Arts in English from Rutgers University and graduated as a distinguished Paul Robeson scholar.

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