Question

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

(b) 4

(c) 2

(d) -2​

Answer 1

Step-by-step explanation:

Here direction of both planes are

A= ( 1,-2,4). and B= (18,17,k)

If both are perpendicular then

A • B = 0

( 1,-2,4) • (18,17,k) = 0

18 - 34 + 4k = 0

4k = 16

k = 4

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