Algebra

Algebra basics calculator for linear equations and substitution.

This page focuses on practical algebra tasks students need every day: solving equations like 2x + 5 = 17 and evaluating expressions after choosing a value for x. It does not claim symbolic CAS-level algebra.

Solve ax + b = c

Equation resultEnter values and solve to see the working.

Evaluate an expression

Substitution resultUse standard operators such as +, -, *, /, and ^.

When this tool helps

  • Intro algebra homework and quiz review.
  • Checking one-variable linear equation steps.
  • Testing whether a value satisfies an expression before graphing.
  • Reviewing substitution and order of operations.
Core principle

To solve ax + b = c, isolate x: subtract b from both sides, then divide by a. That gives x = (c - b) / a when a != 0.

How this differs from the main scientific calculator

The homepage calculator evaluates numeric expressions. This page adds algebra-specific framing around substitution and linear-equation structure.

Worked examples

  1. 2x + 5 = 17: subtract 5 to get 2x = 12, then divide by 2. The answer is x = 6.
  2. 5x - 9 = 11: add 9 to get 5x = 20, so x = 4.
  3. -3x + 12 = 0: subtract 12 to get -3x = -12, then divide by -3. The answer is x = 4.
  4. Evaluate 3x^2 - 2x + 4 when x = 2: 3(4) - 4 + 4 = 12.
  5. Evaluate 4x + 7 when x = -3: -12 + 7 = -5.

Common algebra mistakes

  • Forgetting to perform the same operation on both sides of the equation.
  • Losing a negative sign when moving terms.
  • Ignoring order of operations when substituting into expressions.
  • Thinking division by zero is allowed when a = 0.

FAQ

Can this solve quadratic equations?

No. This page is intentionally limited to linear equations and expression substitution so the page stays honest about what it can do.

What input format should I use?

Use * for multiplication and ^ for powers. Example: 3*x^2 - 2*x + 4.

What if a equals zero?

If a = 0, the equation becomes b = c, which either has no solution or infinitely many solutions depending on the values.

Practice with Examples

Click any example below to automatically fill in the calculator and see the solution.

Solve Equation
2x + 5 = 17
x = 6
Solve Equation
5x - 9 = 11
x = 4
Solve Equation
-3x + 12 = 0
x = 4
Evaluate
3x² - 2x + 4 at x = 2
12
Evaluate
4x + 7 at x = -3
-5
Evaluate
x³ - 3x² + 2x - 1 at x = 2
-1

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Study advice

Work the problem on paper first, then use the tool to verify the final step. That habit builds algebra fluency and keeps you from relying on the calculator as a black box.

Related pages: Scientific Calculator, Fractions, and Essential Algebra Formulas.