The original worked lessons remain the main explanations. Use these focused reminders to check the conditions before you start.
Straight-line equations, intercepts and intersections
Build a complete equation from sufficient information.
Find paired intersection coordinates and interpret intercepts.
Handle parameter cases with zero, one or infinitely many intersections.
Use \(y-y_0=m(x-x_0)\), then check the known point. For an x-intercept set \(y=0\); for a y-intercept set \(x=0\). Both original equations must hold at an intersection. An intercept triangle has area \(\tfrac12|ab|\), where \(a,b\) are the nonzero axis intercepts.