Given lines
y = 2mx + c …(i)
and 2x – y + 5 = 0
⇒ y = 2x + 5 …(ii)
From equations (i) and (ii)
(i) lines will be II if
m1 = m2
⇒ 2m – 2
⇒ m = 1
(ii) lines will be perpendicular if
m1m2 = -1
⇒ 2m × 2 = -1
⇒ m = -1/4
Thus values of m will be 1 and -1/4