Question

two vector are parallel how to find x
give the vector is A= xi+2j-5k and B= 2i+3j-k​

Answer 1

Answer:

if two vectors are parallel then their cross product

should be zero because angle between two parallel

is zero

A×B = ABsin0° = 0

(xi+2j-5k) ×(2i+3j-k) = 0

(-2+15)i-(-x+10)j+(3x-4)k = 0

on comparing,

-x+10 = 0 , 3x-4 = 0

so, x = 10 & x = 4/3 answer

Answer 2

Answer:

If two vector are parallel then their cross product should be zero because angle between two parallel is zero

A × B = ABsin0° = 0

( xi + 2j - 5k) × ( 2i + 3j - k) =0

(-2 + 15)I - (x + 10)j + ( 3x - 4) k =0

-x + 10 = 0, 3x-4= 0

X=10 and X = 4/3.