Question

For what value of n are the lines 4x + 6y = 9 and -3x + ny = 8 perpendicular?

Answer 1

We have:

• (d) 4x + 6y = 9 <=> y = -2/3 x + 3/2
• (d') -3x + ny = 8 <=> y = 3/n x + 8/n

So: (d) ⊥ (d')

=> -2/3 × 3/n = -1

=> -2/n = -1

=> n = -2/-1

=> n = 2

p/s: I'm not sure

Ok done. Thank to me :>