Q.

Consider the lines x(3λ+1)+y(7λ+2)=17λ+5λ being a parameter, all passing through a point P. One of these lines (say L) is farthest from the origin. If the distance of L from the point (3, 6) is d, then the value of d2 is         [2025]

1 15  
2 10  
3 30  
4 20  

Ans.

(4)

We have, x(3λ+1)+y(7λ+2)=17λ+5

 (x+2y5)+λ(3x+7y17)=0

The intersection of family of lines is the point P(1, 2) and let Q(3,6).

Now, d=PQ=22+42=20  d2=20