Algebra 1 Intermediate

No & Infinite Solutions Checker

Enter any two linear equations in Ax + By = C form to instantly determine whether the system has one solution (lines intersect), no solution (parallel lines), or infinite solutions (the same line) — with a visual diagram and step-by-step slope analysis.

Ax + By = C form
Slope-intercept comparison
Visual line diagram
Live
Enter the System
Equation 1 x + y =
x + y = 3
Equation 2 x + y =
x + y = 7
Try an example:
Result
Enter the six coefficients and press Check System to see whether the system has one, no, or infinite solutions.
Step-by-Step Analysis
Visual — Line Relationship
The Three Cases
a₁x + b₁y = c₁
a₂x + b₂y = c₂

Every system of two linear equations falls into exactly one of three categories based on how many times the lines cross:

Consistent (One Solution) — The two lines have different slopes, so they intersect at exactly one point. That point is the solution.

Inconsistent (No Solution) — The two lines have the same slope but different y-intercepts. They are parallel and never meet. The system is called inconsistent. Solution set: ∅

Dependent (Infinite Solutions) — Both equations describe the exact same line. Every point on the line satisfies both equations. The system is called dependent.

Memorize: same slope + different intercept = parallel = no solution. Same slope + same intercept = same line = infinite solutions.
Quick Test — Slopes & Intercepts
Convert to y = mx + b, then compare m and b.

The fastest way to classify any system is to convert both equations to slope-intercept form (y = mx + b) and compare:

  • m₁ ≠ m₂ → different slopes → ONE solution (lines cross)
  • m₁ = m₂ and b₁ ≠ b₂ → parallel → NO solution
  • m₁ = m₂ and b₁ = b₂ → same line → INFINITE solutions

Determinant shortcut: Compute det = a₁b₂ − a₂b₁. If det ≠ 0, there is exactly one solution. If det = 0, check whether the right-hand sides are proportional to decide between no solution and infinite solutions.

Watch out for equations written in non-standard form (e.g. negative b coefficient). Always divide carefully when converting to slope-intercept — sign errors are the most common mistake.

Confused by Parallel Lines or Dependent Systems?

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