Vector Algebra Question 157
Question: If $ \mathbf{a}=(1,-1) $ and $ \mathbf{b}=(-,2,,m) $ are two collinear vectors, then m=
[MP PET 1998]
Options:
A) 4
B) 3
C) 2
D) 0
Show Answer
Answer:
Correct Answer: C
Solution:
- Condition for collinearity, $ \mathbf{b}=\lambda \mathbf{a} $
$ \Rightarrow (-2\mathbf{i}+m\mathbf{j})=\lambda (\mathbf{i}-\mathbf{j}) $ Comparison of coefficient, we get
$ \Rightarrow \lambda =-2 $ and $ -\lambda =m. $ So, $ m=2 $ .
BETA
