Question

Vector <1,2,x> has magnitude of 3. find the value of x if x is a negative number

Answer 1

x = - 2

Explanation:

the magnitude of a vector < a, b, c > is

`√(a^2+b^2+c^2)`

given vector < 1, 2, x > has magnitude of 3 , then

`√(1^2+2^2+x^2)` = 3

`√(1+4+x^2)` = 3

`√(5+x^2)` = 3 ( square both sides to clear the radical )

5 + x² = 3² = 9 ( subtract 5 from both sides )

x² = 4 ( take square root of both sides )

x = ±
`√(4)` = ± 2

since x is negative then x = - 2