How to Find the X Intercept of a Function

A calculator can assist with determing the x-intercept.
••• Jupiterimages/BananaStock/Getty Images

The x-axis is the horizontal axis on a graph, and the y-axis is the vertical axis. The x-intercept is the point a line, represented by a function, where it crosses the x-axis on the graph. The x-intercept is written as (x, 0), because the y-coordinate is always zero at the x-intercept. If you know the slope and the y-intercept of the function, you can calculate the x-intercept using the formula (y - b) / m = x, where m equals the slope, y equals zero, and b equals the y-intercept.

    Substitute the known slope for m and the y-intercept for x in the equation (y - b) / m = x. For example, if the slope equals 5 and the y-intercept equals 3, write the formula as (y - 3) / 5 = x.

    Substitute 0 for y in the equation, since the value of y is zero In this example at the x-intercept. Using the previous example, (y - 3) / 5 = x, the equation becomes (0 - 3) / 5 = x.

    Solve the equation for the value of x. Using the previous example, (0 - 3) / 5 = x, solve the numerator first. Subtract 0 from 3 to get negative three. The result is -3 / 5 = x. Convert the fraction to a decimal by dividing -3 by 5, and the result is -0.6. The x-intercept equals -0.6.

Related Articles

A Description of Parallel & Perpendicular Lines
How to Integrate Sin^2 X
How to Solve a Parabola
How to Find the Slope in a Circle
How to Find a Z Score
How to Divide Rational Numbers
How to Convert Pounds Per Square Foot to PSI
How to Figure Out the Slope of a Line
How to Find Intercepts in a Rational Function
To Calculate Arcsine, What Buttons Do You Press on...
How to Calculate the K Value on a Titration Graph
How to Find the Slope & the Equation of the Tangent...
How to Turn a Negative Denominator into a Positive
How to Do Fractions on a TI-30X IIS
How to Graph and Find the Solution on a Calculator
How to Find a Fraction of a Number
How to Convert a Mixed Number to a Fractional Notation
How to Calculate a Horizontal Tangent Line
How to Factor Binomial Cubes
How to Calculate Arctan