1x−4=2y+1=−3z
2x−λ=4y+1=−5z−2
The shortest distance between the lines
=∣∣d1×d2∣(a−b)⋅(d1×d2)∣
a≡(4,−1,0),b≡(λ,−1,2)
⇒a−b=(4i^−j^)−(λi^−j^+2k^)
⇒a−b=(4−λ)i^−2k^
So, the shortest distance is given by,
D=∣∣i^12j^24k^−3−5∣∣λ−4120242−3−5∣∣
⇒D=∣∣2i^−1j^+0k^∣(λ−4)(−10+12)−0+2(4−4)∣
⇒56=∣52(λ−4)∣
⇒3=∣λ−4∣
⇒λ−4=±3
⇒λ=7,1
So, sum of all possible values of λ is 8.