Key Idea: One Solution (Linear System)
A linear system has one solution when the two equations represent lines with different slopes, meaning they intersect at exactly one point.
General Rule:
Slopes are different.
One point of intersection exists.
This single point satisfies both equations simultaneously.
Why this matters for the SAT:
Identifying when a system has one solution is key to solving systems efficiently, whether by substitution, elimination, or graphing. Different slopes guarantee a unique solution.