Tag Archives: Christopher

Substitution into a formula (calculator method)

Using formulae to solve problems can be fraught with difficulties if some of the numbers are negative. If the calculator is given the values of the letters, then the formulae is keyed in using those letters, accurate results can be achieved every time. The work is also easier to check.

Click here to see a film of the calculator being used to solve this problem.

To set the letter A to the value 12 , B to -3.6 and C to 15

  • 2   Shift   RCL(Sto)   (-)A
  • 7  Shift   RCL(Sto)   ..”’ B
  • -12 Shift   RCL(Sto)   hyp C

Once that is done you can type entire algebra phrases into the calculator and find their values.  Here is an example of using the calculator to use a formula. You will see that the formula is written with capital letters to match the way the calculator sees the alphabet.

Quadratic Formula 001