Solve an equation for x

What this page covers

• Linear equations, including fractions and brackets on both sides.
• Quadratic equations by factoring, completing the square or the formula.
• Equations with a square root or an absolute value, with the check for extraneous solutions.
• Not covered here: systems of two or more equations, inequalities, and equations with the variable in a denominator, which need their own treatment. You can still type one and see what the solver says.

How to enter the problem

• Type it with the = sign. Fractions and powers render as you type, or use the math keyboard.
• Scan it. Fit the one equation in the frame.
• Choose a photo. Several problems in one photo are solved as a list.
• Then tap Solve.

Worked example

Common mistakes

• Reporting both roots of the squared equation. Squaring can add solutions that do not satisfy the original, so the check in the last step is part of the solution.
• Multiplying only the fractions and not every term when clearing denominators. In $\frac{2(x - 3)}{5} = \frac{x + 1}{2} - 1$, the $-1$ must be multiplied by 10 as well.
• Moving a term across the equals sign without changing its sign.
• Dividing both sides by an expression that could be zero, which can lose a solution.

Checks, assumptions and limits

• Check by substitution. Put the answer back into the original equation, not the rearranged one. For the runnable example, $x = -7$ gives $-4$ on both sides.
• Solutions are over the real numbers on this page. A quadratic with a negative discriminant has no real solution; the solver states that rather than inventing one.
• Squaring, and multiplying by an expression containing $x$, are the two steps that can change the solution set. Whenever one is used, the final check is required.
• HexMath can make mistakes. Double check important steps.

Related tasks

• Solve linear equations
• Solve a system of equations
• Solve a formula for a variable
• Solve absolute value equations
• Inequality calculator with steps
• All algebra tasks
• All math tasks