Question

If a vector 2î+3ĵ+8 is perpendicular to the vector 4ĵ-4î+α,then the value of α is:

• A. -2
• B. $\frac{1}{2}$
• C. $-(\frac{1}{2})$
• D. 2

Answer 1

Answer: (C)

$-(\frac{1}{2})$

Answer 2

A =2$\hat{i}$+3$\hat j$+8$\hat k$
B =4$\hat i$−4$\hat j$+a$\hat k$
Given that A and B are parallel, A. B = 0 (2$\hat{i}$+3$\hat j$+8$\hat k$)(4$\hat i$−4$\hat j$+a$\hat k$)
8−12+8a=0
a= $\frac{4}{8}$ = $\frac{1}{2}$