The calculator uses cross multiplication to convert proportions into equations which are then solved using ordinary equation solving methods. Be sure to enter something in each input box before clicking solve. Use the following as a guide:
Any lowercase letter may be used as a variable.
Exponents are supported on variables using the ^ (caret) symbol. For example, to express x2, enter x^2. Note: exponents must be positive integers, no negatives, decimals, or variables. Exponents may not currently be placed on numbers, brackets, or parentheses.
Parentheses and Brackets
Parentheses ( ) and brackets [ ] may be used to group terms as in a standard equation or expression.
Multiplication, Addition, and Subtraction
For addition and subtraction, use the standard + and - symbols respectively. For multiplication, use the * symbol. A * symbol is not necessiary when multiplying a number by a variable. For instance: 2 * x can also be entered as 2x. Similarly, 2 * (x + 5) can also be entered as 2(x + 5); 2x * (5) can be entered as 2x(5). The * is also optional when multiplying parentheses, example: (x + 1)(x - 1).
Order of Operations
The calculator follows the standard order of operations taught by most algebra books - Parentheses, Exponents, Multiplication and Division, Addition and Subtraction. The only exception is that division is not currently supported; attempts to use the / symbol will result in an error.
Division, Square Root, Radicals, Fractions
The above features are not supported at this time. A future release will add this functionality.
If either side of the proportion has a numerator and denominator that share a common factor with a variable, the calculator will report an erroneous solution. Example: 1/2 = x/x will cause the calculator to report 0 as a solution, even though there is no solution. Detection of this type of input is planned as a future enhancement.