X

The x-coordinate of a point where a graph crosses (or touches) the x-axis.

Precisely: A value x = k at which the graph of y = f(x) meets the x-axis, so f(k) = 0; the point is (k, 0).

How it works

Put y = 0 and solve for x. Every x-intercept of the graph of a polynomial is a zero of that polynomial, which is why zeroes can be read off a graph.

Examples

• The line y = 2x + 3 has x-intercept −3/2: it crosses the x-axis at (−3/2, 0).
• The parabola y = x² − 3x − 4 has two x-intercepts, −1 and 4.
• The graph of y = x³ − 4x has three x-intercepts: −2, 0 and 2.

Do not confuse: The x-intercept is where y = 0; the y-intercept is where x = 0. For y = 2x + 3 they are −3/2 and 3.

Used in

graphs of lines and polynomials, zeroes of polynomials, solving equations with a graph

Related

y-intercept, zero of a polynomial, parabola, slope

From

Class 10 Mathematics, Chapter 2: Polynomials