Question

If $\vec{p}=5\hat{i}+\lambda \hat{j} -3 \hat{k} \ and \ \vec{q}=\hat{i}+3\hat{j}-5\hat{k}$, then find the value of λ so that $\vec{p} + \vec{q} \ and \ \vec{p} - \vec{q}$ are perpendicular vectors.

Answer 1

very hard.... help me too