You can easily solve equations using the TI-89 graphing calculator. The key decision for the user is whether to work in the real or the complex number system. For example, let’s solve the quadratic equation, 2x2 - 5x +12 = 0.
To solve the equation in the real number system, press F2 to select the algebra menu, press 1 to select 1:solve( , enter the equation, then press , (comma) X ) ENTER. The TI-89 responds with the answer false, indicating that this equation has no real roots.
To obtain the complex roots, follow the above procedure with the following exception. Instead of selecting 1:solve( , select A:Complex , then select 1:cSolve. The complex roots are
In particular, note that the option 1:solve yields solutions only in the real number system; whereas, cSolve yields solutions in the complex number system.
You may also solve an equation with a constraint. This is handy, for example, in solving trigonometric equations. For example, let’s solve sin(2q ) = 1 for 0 £ q < 2p. The appropriate syntax is:
solve(equation,variable) | constraint.
Here, the entry line is
solve(sin(2x)=1,x) | 0 £ x and x < 2p
Consult the test menu for details on how to enter inequalities and the “and”.