Solve an equation directly in the calculator
Enter a complete equation and let the calculator isolate x automatically, without opening a separate mode.
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When you already have one equation, you can solve it directly in Calculation Mode. You do not need to open a special equation mode or press a calculate key: once the equation is complete, the result appears below it.
This example solves:
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 .Press: -
Step 2
Insert the equation equals sign, then enter . The calculator recognises the complete equation and shows automatically.Press:
Check the result by substituting into the original equation:
It can also rearrange a symbolic equation
The equation does not need to contain only numbers. For example, entering
returns an expression equivalent to
The current Calculator UI has no separate control for choosing a different target variable. In this example, it isolates .
When to use SOLVE instead
Auto Solve 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. On the 991CW-style keypad, choose TOOLS → Solve; on other keypads, use the SOLVE function. For example, applying SOLVE to finds:
Choose the shortest route
| What you have | Use |
|---|---|
| One complete equation such as | Enter it directly and read the automatic result. |
| An expression such as that should equal zero | Use SOLVE (on the 991CW-style keypad: TOOLS → Solve). |
| Several equations that must be solved together | Use System of Equations. |
| A quadratic where you also need the minimum or maximum point | Use Polynomial equation. |
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.