Graph of x³ (the cubic y = x³)
The graph of y = x³ is an S-shaped curve that rises everywhere, from −∞ on the left to +∞ on the right. It flattens out for a moment at the origin, where it changes from bending down to bending up.
Key features
- Domain
- All real numbers
- Range
- All real numbers
- Root
- x = 0 (a triple root)
- Inflection point
- (0, 0), where the tangent is horizontal
- Monotonic
- Increasing everywhere
- Symmetry
- Odd: (−x)³ = −x³, symmetric about the origin
- y-intercept
- None
- Derivative
- 3x2
- Antiderivative
- 14x4+C
Derivative and antiderivative from the calculator’s algebra system. Domain, range and asymptotes are stated for real x.
What the graph of x³ looks like
Unlike x², cubing keeps the sign: negative inputs give negative outputs. So the graph comes up from −∞ in the third quadrant, passes through the origin, and goes on to +∞ in the first.
At the origin the slope 3x² is zero, but the function keeps increasing: this is a stationary point of inflection, not a maximum or minimum. The curve is concave down for x < 0 and concave up for x > 0.
Near the origin the graph is very flat (0.5³ = 0.125), and away from it very steep (3³ = 27). General cubics ax³ + bx² + cx + d keep the S-shape but can have a hump and a dip.
Points of interest
Found numerically to about twelve digits in the window −3 ≤ x ≤ 3, then shown in exact form where one exists.
- x-intercepts (roots)
- x = 0
- Local maxima
- None in this window
- Local minima
- None in this window
- Inflection points
- (0, 0)
Table of values
A few points to plot, with exact values where they are simple.
| x | y = x³ |
|---|---|
| −3 | −27 |
| −2 | −8 |
| −1 | −1 |
| 0 | 0 |
| 1 | 1 |
| 2 | 8 |
| 3 | 27 |
How to graph x³ by hand
- 1Plot (0, 0), (1, 1), (−1, −1), (2, 8) and (−2, −8).
- 2Add (0.5, 0.125) and (−0.5, −0.125) to capture the flat stretch near the origin.
- 3Draw a smooth S-curve that is horizontal at the origin and steepens outward.
Transformations
How the graph moves when you change the formula. The original is x³ in blue.
y = (x - 1)^3 + 2The inflection point moves to (1, 2).y = -x^3Reflected: now decreasing everywhere.y = x^3 - 3xAdding −3x creates a local maximum at (−1, 2) and a minimum at (1, −2).
Frequently asked questions
What is the shape of the graph of x³?
Does y = x³ have a maximum or minimum?
Is x³ odd or even?
What is the range of a cubic function?
Related graphs
The basic parabola: vertex (0, 0), opens upward.
Defined for all x; vertical tangent at the origin.
A straight line: slope m, y-intercept b.
(eˣ − e⁻ˣ)/2: odd, increasing, through the origin.
A hyperbola with asymptotes along both axes.
Starts at the origin; half of a sideways parabola.
Change the window, add sliders for a, b, h and k, trace the curve with your keyboard, or overlay its derivative.