Question

If the lines kx – y + 4 = 0 and 2y = 6x + 7 are perpendicular to each other, find the value of k.

Answer 1

Given lines are

kx – y + 4 = 0

And 2y = 6x + 7

Or y = kx + 4   ...(i)

And y = `3x + 7/2`   ...(ii)

On comparing with y = m_x + c, we get

m₁ = k and m₂ = 3

If lines are perpendicular, then

m₁m₂ = – 1

`\implies` k × 3 = – 1

`\implies` k = `(-1)/3`