What you can type
Numbers, x, brackets, + − × ÷ and ^ for powers. The functions sin, cos, tan, sqrt, ln, log, exp and abs are all available, along with pi and e.
Implicit multiplication works, so 2x^2 and 3sin(x) mean what they look like.
Worked example
Plotting x^2 - 4 over −5 to 5 gives a parabola crossing the x-axis at x = −2 and x = 2, and the y-axis at −4.
Its only turning point in that window is (0, −4), which is the minimum.
How the crossings are found
The curve is sampled across the window and each change of sign is narrowed down until the crossing is pinned to six decimal places.
A jump between branches, such as 1/x at zero, is rejected rather than reported as a root, because the curve never actually reaches the axis there.
Reading the plot
Every curve is followed by a table of the same numbers, so the shape is never the only way to read the answer.
Where the function has no value, the curve is drawn with a gap rather than joined across it.
Inputs for the graphing calculator
Function of x
Type the expression. Powers use ^, and brackets work as you would expect.
Plot from and to
The left and right edges of the window, up to 200 units apart.
Value at x =
The point where f(x) is worked out for the headline answer.
CALCULATOR QUESTIONS
Graphing calculator questions
How do I plot x squared minus 4?
Type x^2 - 4. The curve crosses the x-axis at −2 and 2, and the y-axis at −4.
Can I plot sin(x)?
Yes. sin, cos, tan, sqrt, ln, log, exp and abs all work, and so do pi and e.
Why does the curve have gaps?
Some functions have no value at some points, such as 1/x at zero. The plot leaves a gap there rather than inventing a line across it.
How are the roots found?
Numerically: the window is sampled, every change of sign is narrowed down, and the crossing is reported to six decimal places.