Question

The lines whose equations are 2x + 3y = 4 and y = mx + 6 will be perpendicular when

Answer 1

These lines will be perpendicular when m = ³⁄₂

Explanation:

Two lines are perpendicular when the product of their gradients equal to -1. So:

m₁ * m₂ = -1

Let's get the first equation in gradient-intercept form (same as equation two).

2x + 3y = 4

3y = -2x + 4

y = -⅔x + ⁴⁄₃

We know the first gradient, and now we can find the gradient of the second line (which when multiplied will result in -1 as these lines are perpendicular). So:

-⅔ * m₂ = -1

m₂ = ³⁄₂