Question

How do I graph a quadratic function on a $TI-84$ calculator ?

Answer 1

Hint: To enter a quadratic equation in $TI-84$ calculator, we need to enter the digits, letters, signs, parenthesis or anything else one by one by pressing the keys. At first we enter the coefficient of $x^2$ and then $x$ and then squaring it with the help of the “ $x^2$ “ key. Gradually, we enter the remaining terms followed by pressing the “GRAPH” key to plot the graph.

Complete step-by-step answer:
The general equation of a quadratic equation is
$y=a{x}^2+bx+c$
For the sake of understanding this problem, let us take $a=2$ , $b=1$ , and $c=-1$ . The equation thus becomes
$\Rightarrow y=2x^2+x-1$
At first, we press the “ $Y=$ ” key under the “stat plot f1” heading. The screen of the calculator changes to let us enter an equation. We enter the coefficient of $x^2$ which is $2$ by pressing the corresponding key. We then enter $x$ by pressing the “ $X,T,n$ “ key under the “LINK” heading. Then, we need to square this $x$ by pressing the “ $x^2$ ” key which automatically squares the $x$ . Then, we need to enter the coefficient of $x$ which is $1$ in this case. We enter $1$ by pressing the corresponding key. Then, we need to enter the constant term which is $-1$ in this case. We enter the negative sign using the “ $-$ ” key at the right side of the calculator. After that, we enter $1$ using the corresponding key.
Finally, we command the calculator to plot the graph by pressing the “GRAPH” key under the “TABLE F5” heading at the top right corner of the calculator. The calculator takes some time, though in milliseconds, to show the corresponding graph of the equation entered by us.

Note: In case of any fractional coefficients, we need to enter parenthesis using the “ $($ ” and the “ $)$ ” keys and write the fractions within this parenthesis. We should also remember that if we need to write any negative numbers at the start of the equation or expression, then we must use the “ $(-)$ ” key instead of the usual “ $-$ ” key to avoid any errors.