General point on line L:1x−1=−1y+1=2z−2 is (λ+1,−λ−1,2λ+2) 
DR's of PM are (λ,−λ−3,2λ) PM⊥L $\begin{aligned}
& \Rightarrow \lambda+(-1)(-\lambda-3)+2(2 \lambda)=0 \
& \Rightarrow 6 \lambda+3=0
\end{aligned}$
P(21,2−1,1) Let another line L′:1x+1=−1y−1=1z+2 General point on line L′ is (μ−1,−μ+1,μ−2) Point of intersection of line L and L′ is $\begin{array}{l|l}
\lambda+1=\mu-1 & 2 \lambda+2=\mu-2 \
\Rightarrow \mu-\lambda=2 \ldots(1) & \Rightarrow 2 \lambda=\mu-4
\end{array}$
Q(−1,1,−2)2(PQ)2=2((21+1)2+(2−1−1)2+(1+2)2)=2(49+49+9)=27