Consider the following equations of straight lines : Line L_1: 2x – 3y = 5; Line L_2 : 3x + 2y = 8; Line L_3 : 4x-6y = 5; Line L_4 : 6x-9y = 6. which one of the following is the correct statement?

Previously Asked in : Gate CE-afternoon season 2022 ||

L4 is perpendicular to L2 and L4 is parallel to L3

L1 is parallel to L2 and L1 is perpendicular to L3

L2 is parallel to L4 and L2 is perpendicular to L1

L3 is perpendicular to L4 and L3 is parallel to L2

Answer (Detailed Solution Below)

Option L 4 is parallel to L 2 and L4 is parallel to L3 is correct

Detailed Solution :

Line L_1 : 2x-3y = 5\\ y = \dfrac {4x-5} {3}

\therefore \, \dfrac {dy} {dx} \, = \, \dfrac {2} {3}

Similarly for other lines

\textrm {Line} \, L_2 : 3x + 2y = 8 \\ \dfrac {dy} {dx} \, = \, \dfrac {-3} {2} \\ \textrm{Line} \, L_3 : 4x -6y = 5 \\ \dfrac {dy} {dx} \, = \, \dfrac{2} {3} \\ \textrm {Line} \, L_4 : 6x -9y = 6 \\ \dfrac {dy} {dx} \, = \, \dfrac{2} {3}

\therefore \quad \left (\dfrac{dy}{dx}\right)_{L_1} = \, \left (\dfrac{dy} {dx} \right)_{L_3} = \, \left (\dfrac {dy}{dx} \right)_{L_4} = \, \dfrac {2}{3}

and \left(\frac{dy}{dx} \right)_{L_2} \times \left(\frac{dy}{dx}\right)_{L_1} = \left(\frac{dy}{dx} \right)_{L_2} \times \left( \frac{dy} {dx} \right)_{L_3} = \left (\frac{dy} {dx} \right)_{L_2} \times \left (\frac{dy}{dx} \right)_{L_4} = -1

\therefore L1, L3, L4 are parallel to each other and perpendicular to L2 .

Correct option is: L 4 is parallel to L 2 and L4 is parallel to L3

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