Formulas > Using formulas
12345Using formulas

Theory

A formula, describing the relation between the variables x and y , is called y as a function of x , when this formula appears as y = ... . The x -values are the input values, the y -values are the outcomes. In the corresponding graph the y -values are always found on the vertical axis.

  • In the formula y = x 2 + 4 , y ia a function of x . When you substitute x = 3 , the outcome is y = 13 . Notation: y ( 3 ) = 13 .

  • In the formula P = 0.052 v 3 , P is a function of x . When you substitute v = 10 , the outcome is P = 52 . Notation: P ( 10 ) = 52 .

Formulas such as y = ... can be entered into your graphic calculator.

Occasionally you need to re-write the formula to be able to enter it into your graphic calculator. When you re-write you should use the following rules:

  • you may add or subtract the same amount on both sides of the equal sign;

  • you may multiply or divide by the same amount on both sides of the equal sign (with the exception of multiplying or dividing by 0 );

  • and occasionally you need to remove the brackets first.

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