Graphing calculator

Type an expression in the list on the left; each line is drawn in its own colour.

• Functions: x^2 - 4 or y = sin x.
• Equations in x and y: x^2 + y^2 = 25 draws a circle.
• Vertical lines: x = 3.
• Points: (2, 1).
• Sliders: use a letter like $a$ in y = a x^2, then press Add a slider: a. Drag it and watch the graph change.

Drag the graph to pan, and scroll or pinch to zoom. Hover over (or touch) a curve to read off coordinates. Click a curve to mark its roots, turning points and intersections with the other curves.

Open a function's options to add:

• Derivative, which draws $f'(x)$ as a dashed curve.
• Tangent at $x = a$, which draws the tangent line $y = f(a) + f'(a)(x - a)$ and gives its gradient.
• Area from $a$ to $b$, which shades the region and gives $\int_a^b f(x)\,dx$. Area below the axis counts as negative, as in calculus.

Derivatives are worked out symbolically and areas are computed numerically with adaptive Simpson's rule, accurate to well beyond the digits shown.

Where a function isn't defined, such as $1/x$ at $x = 0$, $\tan x$ at $x = \pi/2$, or $\sqrt{x}$ for $x < 0$, the graph leaves a gap instead of joining the pieces with a false vertical line.