Solve three linear equations in three unknowns
Enter the coefficients of a three-equation system and verify x, y, and z.
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When a linear-algebra exercise gives you three equations in , , and , the hard part on a coefficient-entry calculator is often putting each number in the right column. Use this system to practise:
Write each equation as . Enter its coefficients in the order , , , right-hand side. That gives the rows , , and .
Enter and solve the system
Below each step is the screen you should see after pressing.
Next to each step is the screen you should see after pressing.
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Step 1
Open the mode picker. On the 991CW-style keypad, choose HOME → Equation → Simultaneous → 3 unknowns; on other keypads, choose System of Equations → 3 unknowns. The three-row coefficient grid appears.Press:
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Step 2
Enter across the first row and across the second. Press the equals key after each number to advance one box.Press: -
Step 3
Enter across the last row. Confirm its last box with the equals key, then read all three results .Press:
Verify all three equations
CalcES returns . Substitute the values back into every original equation:
If one check fails, inspect that equation's row, especially the sign in its or column. For work that requires an algebraic solution, use the displayed values to check your elimination or substitution steps rather than presenting the calculator output as the working.
Solve a three-variable system on your fx-991EX calculator
Enter the coefficients of three equations and get x, y, and z together — the keypad matches a real Casio calculator.