UPSC NDA Math Model Paper 3

Here, 3x + y + 3z = 8 and 9x + 3y + 9z = 15
Divide 9x + 3y + 9z = 15 by 3 we get
3x + y + 3z = 5
Now, distance between 3x + y + 3z = 8 and 3x + y + 3z = 5
=|

8−5

√32+12+32

|=

3

√19

Hence, option (3) is correct.