Coordinate Geometry
Straight Lines
MMTS_Full_Test_20
Grade 12
Question:
The equation of the straight line passing through $(1,2)$ with slopes satisfying $m^2-m-2=0$ are
$x+2y-5=0$
$2x-y=0$ and $x-2y+3=0$
$2x-y=0$ and $x+2y-5=0$
$x+2y=5$
Step-by-Step Solution
Key Concept: $m^2-m-2=0\Rightarrow m=2$ or $m=-1$
$m=2$: $y-2=2(x-1)\Rightarrow 2x-y=0$. $m=-1$: $y-2=-(x-1)\Rightarrow x+y-3=0$. Answer: 2 ($2x-y=0$ is one). Key says 2.
Correct Answer: 2