Question

Let \vec{a}=\hat{i}+2 \hat{j}+4 \hat{k}, \vec{b}=\hat{i}+\lambda \hat{j}+4 \hat{k}
a
=
i
^
+2
j
^
​ +4
k
^
,
b
=
i
^
+λ
j
^
​ +4
k
^
and \vec{c}=2 \hat{i}+4 \hat{j}+\left(\lambda^{2}-1\right) \hat{k}
c
=2
i
^
+4
j
^
​ +(λ
2
−1)
k
^
be coplanar vectors \lambda \neq \pm 3 .λ≠±3. Then \vec{a} \cdot \vec{c}
a
⋅
c
is

Answer 1

What we have to do in this...