Quadratic Formula – TI-84 Evo Math Program

Type a, b, and c and this program prints both solutions to ax² + bx + c = 0, with no formula to key in by hand.

Send it to your calculator

Plug the calculator into your computer with a USB cable, then use the button below. If something is not working, see troubleshooting.

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Press the prgm key. The PROGRAMMING menu opens.
Press enter to select TI-Basic. The list of TI-Basic programs opens.
Press enter on QUAD in the program list, which puts prgmQUAD on the home screen.
Press enter to run it. The program prints the standard form AX²+BX+C=0 as a reminder of what each letter stands for, then asks for the first coefficient with an A? prompt.

Type a, b, and c, pressing enter after each. For x² − 5x + 6, that's A = 1, then B = −5 (use the negative key, just left of enter, for the minus), then C = 6. The moment you enter C, it lists both solutions, labeled so you can read them off at a glance: X = 3 and X = 2.

To solve another one, just press enter on the home screen. The calculator reruns the program and the A? prompt comes right back.

It's the quadratic formula, worked out for you. Behind the scenes the program evaluates x = (−b ± √(b² − 4ac)) / (2a) from the a, b, and c you type, so you get both roots without keying that whole expression in by hand.
A repeated solution shows up twice. x² − 4x + 4 has the one solution 2, so the program prints X = 2 and X = 2. That doubled answer is your signal the parabola just touches the x-axis at a single point.
Complex roots are supported. When the part under the square root is negative, the program says there are no real solutions and then prints both complex roots. For x² + 1 it gives X = i and X = −i. It switches the calculator to a+bi mode for the calculation and leaves that mode on.
Enter 0 for A and it isn't a quadratic. With no x² term, the program answers "Not a quadratic."