Function evaluator and grapher

Graph

Drag to pan, scroll or pinch to zoom, or use the + / − / ⟲ buttons. The graph can also be reached with the keyboard: Tab to it, then use the arrow keys and + / −.

Formula

How it works

Choose a family of functions and its coefficients a, b, c, then enter the x-value to evaluate f(x) there. The graph below plots the same function so you can see its shape.

Worked example

The same calculation with the default values:

• Function family Quadratic: f(x) = ax² + bx + c
• Coefficient a 1
• Coefficient b 0
• Constant c 0
• x 2

1. f(2) = 1×2² + 0×2 + 0 = 4

Result: f(x): 4 · Domain: All real numbers · Range: y ≥ c − b²÷4a if a > 0, or y ≤ c − b²÷4a if a < 0

Common mistakes

• Entering an x value outside the function's domain (e.g. x = 0 for the reciprocal family), which is undefined rather than zero.
• Confusing the b coefficient's role across families - it is an added term for linear/quadratic/cubic, but a frequency/rate inside sin, cos or e^(...) for the trigonometric and exponential families.
• Reading the graph's shape without checking the actual a/b/c values entered - a small change in a can flip a curve's direction entirely.