program quadratic formula in ti 84 plus?

Press [Prgm] > New > 1:Create New... Type in a name. I'll use QUADFORM in this example.

Here's one possible source code for a quadratic formula program:

PrgmQUADFORM

:Prompt A,B,C

:Pause (-B+{1,-1}√(B²+4ACi²))/(2A►Frac

The program handles both real and complex answers and outputs them in a list. If a number can be converted to a fraction it will be (like .33333333333... to ⅓).

Prompt and Pause can be found under [Prgm] and [Prgm] > I/O.

►Frac can be found under [Math].

The i in the program is the imaginary unit, [2nd][.].