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How to Graph Pre-Algebra Functions

A strong understanding of functions is critically important to comprehend mathematics in general. In pre-algebra, which is normally taught during the middle school years, students are introduced to linear equations, the most basic type of function, and taught how to graph them. Graphing linear equations requires students to understand input, output, slope, intercept, variables and a host of other concepts which will reappear throughout the rest of their education.

Things You'll Need

  • Coordinate grid
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Instructions

    • 1

      Examine the function, and determine whether or not it is written in standard form; standard form makes the equation conform to a y=mx+b pattern. Leave the equation alone if the y-variable is isolated on one side of the equal sign. However, rearrange the equation algebraically if y is being added to, subtracted from, divided by or multiplied by any other term. Make sure that on the side of the equation opposite the y-variable, the x-term appears before the (constant) number, if any.

    • 2

      Look at the x-variable of the function, and notice whether any number appears directly before it; for example, the number 4 appears before the x-variable in the function y=4x+3. Write down that number to the side and set it equal to the word "slope," or "m," as in m=4. Reexamine the function and identify the number, otherwise known as the y-intercept, that is being added to or subtracted from the x-term; in the example y=4x+3, the y-intercept would be 3. Write the y-intercept value below the slope value to the side, equal to either the word "intercept" or "b."

    • 3

      Take out your coordinate grid. Label each tick-mark of the y-axis from the origin, or zero, up and down to 10 and -10. Repeat the labeling for each tick of the x-axis, also out to 10 and -10. Look down at the y-intercept and count that many tick marks up or down the y-axis, up if the intercept is positive and down if negative, and draw a small circle, or point, at that location.

    • 4

      Look at the slope, or m, you previously identified. If the number is a whole, non-fractional number, draw a line under the number and add a one beneath the line, making the number a fraction (for example, 4 will become 4/1). Place your pencil on the y-intercept point you made on the y-axis of your coordinate plane. Count up the y-axis as many tick marks as the top of the slope fraction dictates; for example, 4 tick marks in the slope fraction 4/1. Count as many tick-marks to the right as the bottom of the fraction dictates. Make a point where your pencil comes to rest. Reverse the "up and to the right" formula to "down and to the right" if the slope is a negative number. Connect the y-intercept point with the new point with a straight-edge to finish the graph of the linear function.

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