Projection of $\hat{i}+2 \hat{j}+3 \hat{k}$ on $\hat{i}-2 \hat{j}-2 \hat{k}$ is equal to:

3 -3 9 -9

-3

Projection of $\vec{a}$ on $\vec{b}$ is $\frac{\vec{a} . \vec{b}}{|\vec{b}|}$ Thus required projection $=\frac{(\hat{i}+2 \hat{j}+3 \hat{k}) .(\hat{i}-2 \hat{j}-2 \hat{k})}{\sqrt{1+4+4}}$ $=\frac{1-4-6}{3}=-3$ Hence (2) is correct answer.