Linear Equation Solver

Enter the coefficients of your equation ax + b = c to solve for x instantly.

How it is calculated

The tool solves a·x + b = c by isolating x: subtract b from both sides, then divide by a, so x = (c − b) / a. You enter the three numbers a, b and c exactly as they appear in the equation, with their signs. The result is rounded to four decimals, so a repeating value such as one third is shown as 0.3333; only that rounded value is displayed, not the intermediate steps. If a is zero, the equation has no single solution (either none or infinitely many), so the tool returns no result. Negative and decimal coefficients are accepted. To handle an equation with x on both sides, first collect the x terms into one coefficient a.

Worked example

Solve 4x + 5 = 22, so a = 4, b = 5, c = 22. Step 1: subtract b from both sides, 22 − 5 = 17. Step 2: divide by a, 17 / 4 = 4.25. The tool prints 4.2500. Check: 4 × 4.25 + 5 = 17 + 5 = 22, as required.

Try this example →

Common mistakes

  • Entering b with the wrong sign. For 4x − 5 = 22 you must type b = −5, which gives x = 6.75, not 4.25.
  • Dividing by a before subtracting b, which gives (c / a) − b. The offset b has to be removed first.
  • Entering an equation like 3x + 2 = x + 10 directly. Move the x terms first: 2x + 2 = 10, so a = 2, b = 2, c = 10.
  • Entering a = 0 when the unknown cancels out. Such an equation has no single answer and the tool returns nothing.

About this calculator

An equation of the form ax + b = c is the standard first-degree (linear) equation taught at the start of algebra: a single unknown, x, appears only to the first power, multiplied by a coefficient a and offset by a constant b, set equal to another constant c. Solving it is a two-step isolation process — subtract b from both sides, then divide by a — and it's the algebraic building block that every more complex equation (quadratics, systems of equations, word problems) eventually reduces to at some step.

Students use a linear equation solver to check the final answer of their homework against their own working (the calculator shows the result, not the individual steps), while the same ax + b = c structure shows up constantly outside the classroom wherever a quantity scales proportionally with an offset — converting units, splitting a fixed cost across a variable number of items, or working out a break-even point in a simple pricing model.

This calculator takes the coefficients a, b, and c and returns the value of x rounded to four decimal places. The coefficient a cannot be zero.

Was this helpful?

You can pick up to 3 reactions.

Comments

  • Be the first to comment.

Popular calculators

All Calculators