Let a,b,c be the direction ratios of the required line. Since the line is perpendicular to the lines with d.r.s. 1,2,3 and −3,2,5. ∴a+2b+3c=0. . . . (i) and −3a+2b+5c=0. . . . (ii) ⇒
a
2
=
b
−7
=
c
4
[From (i) and (ii)] ∴ Equation of the required line is