Straight Lines
Pair of Straight Lines
AIEEE 2004
Grade 11
Question:
If one of the lines given by $6x^2 - xy + 4cy^2 = 0$ is $3x + 4y = 0$, then $c$ equals:
(1) $1$
(2) $-3$
(3) $3$
(4) $-1$
Step-by-Step Solution
Key Concept: Substitute $y = -3x/4$ (from $3x + 4y = 0$) into $6x^2 - xy + 4cy^2 = 0$. Simplify (divide by $x^2$) and solve for $c$.
The detailed step-by-step mathematical proof is available inside the Mathbee app workspace.
Correct Answer: (2)