MHT CET 2017 Math Solved Paper

(c) We have, pair of lines
kx2+5xy+y2 = 0 ...(i)
After comparing eq. (i) with
ax2+2hx+by2 = 0, we get
a = k,b = 1 and 2h = 5
Suppose m1 and m2 are two slopes of pair of lines
Then m1+m2 =

−2h

b

=−5 and m1m2=

a

b

=k
As, (m1−m2)2 = (m1+m2)2−4m1m2
⇒ (1)2=(−5)2−4k
⇒ 4k=24⇒k=6