Help in Entering Equations

Entering Basic Equations

Mathematical Form
Input (Keyboard) Form
  2 x – 3 y = 4
2x-3y=4
x2 +2 y2 = 3
x^2+2y^2=3
xy4/3 = –2
x-y^(4/3)=-2

Always use x and y (or X and Y) as your equation variables. Be sure to include the equals sign, "=".

To enter an equation, you can use your computer keyboard interchangably with one of the calculator keypads.

You can use parentheses, ( ), square brackets, [ ], or curly braces, { }, to group terms.

Terms in x and y may be entered as sums, differences, products, and quotients of numbers (coefficients) times powers in x and/or y. You can use "*" for multiplication, or in the case of a number times x, you can abbreviate, say, "3*x" by "3x" but not "x3"; also, "x*y" cannot be abbreviated to "xy".

Coefficients may be entered as integers (like 2 or –3), rational numbers (ratios of integers, like (1/2) or (–5/4)), or decimals (like 1.52 or –7.6). We automatically convert all decimals to their rational number equivalents (for example, 1.52 = 38/25). Fractional powers can be entered using parentheses, as in 3^(1/2) or x^(-1/3).

Use pi for π (approximately 3.14) and e for the base e (approximately 2.72) of natural logarithms.


Entering Intermediate and Advanced Equations

Mathematical Form
Input (Keyboard) Form
y = |x|
y=abs(x)
y =
y=sqrt(x)
y = logex
y=log(x) or y=ln(x) or y=log(e,x)
y = log5x
y=log(5,x)
y = tan x
y=tan(x)
y = sin 2πx
y=sin(2pix) or y=sin(2pi*x)

When entering any function with an abbreviated name, like sin for sine, the argument (term in x) following the name needs to be enclosed in paired parentheses. So, "sinx" is incorrect, as is "sin(x", but "sin(x)" is correct.

Logarithmic Functions. Logarithmic functions can be entered with one argument, as in log(x), or two arguments, as in log(b, x), where b is the base, b > 0, b ≠ 1. When only one argument is used, it refers to the logarithm to the base e, so log(x)=log(e, x), where e≈ 2.72 is the base of the natural logarithms. The natural logarithm can also be entered as ln(x). Exponential functions can be entered conveniently using the power symbol, as in e^x or 2^(x^2–1).

More Information

For further illustrations of valid input, see how equations are entered in the Basic Equation Plotting Examples.

 

 

       

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