CBSE Class 12 Math 2009 Solved Paper

© examsnet.com
Question : 8
Total: 29
Write the value of p for which
a
= 3
^
i
+2
^
j
+9
^
k
and
b
=
^
i
+p
^
j
+3
^
k
are parallel vectors.
Solution:  
Two vectors
a
and
b
are parallel
a
= 3
^
i
+2
^
j
+9
^
k
and
b
=
^
i
+p
^
j
+3
^
k

a
= λ
b

So 3
^
i
+2
^
j
+9
^
k
= λ (
^
i
+p
^
j
+3
^
k
)

3
^
i
+2
^
j
+9
^
k
= λ
^
i
+λp
^
j
+λ3
^
k

⇒ λ = 3 , pλ = 2 and 9 = 3λ
⇒ p =
2
3
© examsnet.com
Go to Question: