- AExactly one
- BNone
- CInfinitely many
Step-by-Step Solution
a₁/a₂ = 1/2; b₁/b₂ = 2/4 = 1/2; c₁/c₂ = 4/12 = 1/3. First two equal but third differs → parallel → no solution.
Answer: B) None
How many solutions does and have?
Class 10Pair of Linear Equations in Two VariablesAlgebra — Systems of Equations
Key idea: Three geometric possibilities
Two lines in a plane can:
1. **Intersect at a single point** → exactly ONE solution. (Independent, consistent.)
2. **Be parallel and distinct** → NO solution. (Inconsistent.)
3. **Coincide (be the same line)** → INFINITELY many solutions. (Dependent, consistent.)
These three cases are decided by comparing the coefficient ratios:
| Condition on a₁/a₂, b₁/b₂, c₁/c₂ | Type | # solutions |
|---|---|---|
| a₁/a₂ ≠ b₁/b₂ | Lines intersect | One |
| a₁/a₂ = b₁/b₂ ≠ c₁/c₂ | Parallel | None |
| a₁/a₂ = b₁/b₂ = c₁/c₂ | Coincident | Infinitely many |
1. **Intersect at a single point** → exactly ONE solution. (Independent, consistent.)
2. **Be parallel and distinct** → NO solution. (Inconsistent.)
3. **Coincide (be the same line)** → INFINITELY many solutions. (Dependent, consistent.)
These three cases are decided by comparing the coefficient ratios:
| Condition on a₁/a₂, b₁/b₂, c₁/c₂ | Type | # solutions |
|---|---|---|
| a₁/a₂ ≠ b₁/b₂ | Lines intersect | One |
| a₁/a₂ = b₁/b₂ ≠ c₁/c₂ | Parallel | None |
| a₁/a₂ = b₁/b₂ = c₁/c₂ | Coincident | Infinitely many |
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