Question

The two planes x – 2y + 4z = 10 and 18x + 17y + kz = 50 are perpendicular, if k is equal to ______.

Options

• – 4

• 4

• 2

• – 2

Answer 1

The two planes x – 2y + 4z = 10 and 18x + 17y + kz = 50 are perpendicular, if k is equal to 4.

Explanation:

Given, x – 2y + 4z = 10 and 18x + 17y + kz = 50 are perpendicular

∵ (1)(18) + (–2)(17) + (4)(k) = 0

18 – 34 + 4k = 0

–16 + 4k = 0

4k = 16

k = 4