Linear Equation Solver – ax + b = 0 Steps
Solve ax+b=0 directly: x=−b/a.
- Handles fractions, decimals and the a=0 edge cases — 3x+12=0 gives x=−4, verified by substitution.
Figures are estimates from this calculator’s standard formula — adjust the inputs in the tool below for your exact number.
How the Linear Equation Solver Works
A linear equation in one variable isolates x in a single move: subtract b, then divide by a. Take 3x + 12 = 0. Subtract 12 from both sides to get 3x = -12, then divide by 3, giving x = -4. Verification by substitution returns 3(-4) + 12 = -12 + 12 = 0, confirming the root. The solver handles fractional coefficients such as (2/3)x - 4 = 0, where multiplying both sides by 3/2 yields x = 6, and decimals like 0.5x = 7 with x = 14. Edge cases are flagged explicitly: if a = 0 and b ≠ 0 the equation has no solution (0x = -b is impossible), while a = 0 and b = 0 is an identity true for every x. Each transformation is printed so the method mirrors standard algebra classwork.
- 1
Enter a and b
Type the coefficients of ax + b = 0
- 2
Isolate the x term
Subtract b from both sides: ax = -b
- 3
Divide by a
Compute x = -b/a, exact or decimal as needed
- 4
Verify the solution
Substitute x back; the left side must equal 0
Use Cases
Break-Even Price
Solve 25x - 1500 = 0 to find 60 units cover a 1,500 fixed cost
Temperature Conversion
Find when °C equals °F: solve 1.8x + 32 = x, giving x = -40
Budget Lines
Determine the quantity where income equals expense
Tips
- 1
One linear equation in one unknown always has exactly one root when a ≠ 0
- 2
Fractional coefficients clear instantly when you multiply by the LCD
- 3
Substitution is the fastest error check for any solved x
Common Mistakes
Dividing only the bx side by a and leaving b undivided
Sign slip moving b across the equals sign: 3x = -12, not +12
Missing the a = 0 special cases — no solution or infinitely many
Rounding decimals too early and losing exact checks
FAQs
How do I solve 3x + 12 = 0?
What if a equals 0?
How do I handle fractions like (2/3)x - 4 = 0?
Where do Celsius and Fahrenheit meet?
Does the solver show steps?
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