Question

The vectors (4,2,−1) and (10x,5x,100) are perpendicular. Find x.

Answer 1

x = 2

Explanation:

given the vectors are perpendicular then their dot product is zero

(4 , 2 , - 1) • (10x , 5x , 100) = 0

sum the products of corresponding components

4(10x) + 2(5x) - 1(100) = 0

40x + 10x - 100 = 0 ( add 100 to both sides )

50x = 100 ( divide both sides by 50 )

x = 2