Solve an equation directly in the calculator

Enter a complete equation and let the calculator isolate x automatically, without opening a separate mode.

2 étapes

Cet article n’est pas encore disponible en français. La version anglaise complète est affichée.

Solve one equation directly in Calculate, without opening a special equation mode. As soon as the equation is complete, its answer appears below it; pressing the equals key confirms it.

This example solves:

2 x + 3 = 7

Enter the equation

Below each step is the screen you should see after pressing.

Next to each step is the screen you should see after pressing.

Step 1

Enter the left-hand side $2 x + 3$ .

Press:
Step 2

Insert the equation equals sign, then enter $7$ . The calculator recognises the complete equation and shows $x = 2$ automatically.

Press:

Check the result by substituting $x = 2$ into the original equation:

2 (2) + 3 = 7

If the answer is True or False instead of $x = 2$ , Verify is on, and a check-mark icon shows in the function bar. Tap that icon to turn Verify off.

It can also rearrange a symbolic equation

The equation does not need to contain only numbers. For example, entering

a x + b = c

with $a$ , $b$ , and $c$ unset and pressing the equals key shows:

x = - \frac{b}{a} + \frac{c}{a}

If $a = 2$ , $b = 3$ , and $c = 7$ are stored first, pressing the equals key uses those values and gives $x = 2$ . Either way, the equation is solved for $x$ .

Use the answer in the next calculation

When the equation has one answer, pressing the equals key also stores it in $x$ and in Ans. After $2 x + 3 = 7$ , Ans holds $2$ , and entering $x^{2}$ then pressing the equals key gives $4$ .

An equation with several answers, such as $x^{2} = 4$ , stores none of them. To keep one, tap the Save icon under the answer and pick it, as in save an answer without STO.

When to use SOLVE instead

Solving directly starts when the input is a complete equation containing an equals sign. If you have an expression and want to solve where it equals zero, enter the expression and press for SOLVE. For example, applying SOLVE to $x^{2} - 2$ needs no starting value and finds:

x = - 2, x = 2

Choose the shortest route

What you have	Use
One complete equation such as $2 x + 3 = 7$	Enter it directly and read the automatic result.
An expression such as $x^{2} - 2$ that should equal zero	Use SOLVE ().
Several equations that must be solved together	Use simultaneous equations, with two or three unknowns.
A quadratic where you also need the minimum or maximum point	Use the polynomial solver.

The fx-991EX screen showing 2x + 3 = 7 solved automatically as x = 2.

Solve an equation directly on your fx-991EX calculator

Type 2x + 3 = 7 and watch the calculator isolate x automatically — free, right in your browser.

Solve it now More guides