Flag Analytical Geometry> two pair of straight lines have the equat...
question mark

two pair of straight lines have the equations y2+xy-12x2=0 and ax2+2hxy+by2=0.one line will be common among them if??

alekhya , 8 Years ago
Grade 12th pass
anser 2 Answers
Gopal Gopakumar

Last Activity: 8 Years ago

The equation of the given lines can be written as (y + 4x)(y – 3x) = 0
so the roots of y/x are either –4 or 3.
now rearranging the given equation,
 
b(y/x)2 + 2h(y/x) + a = 0
 
they will have a common line only if -4 or 3 is a root of the rearranged equation.
substituting values,
9b + 6h + a = 0    or 16b – 8h + a = 0
 
Thanks!

Shaik Asad

Last Activity: 6 Years ago

Question - Two pairs of straight lines have eqns (1) and( 2)-[equations are given in solution]. One line will be common if ?
(A) a=-3(2h+3b)  (B)a=8(h-2b) (C) a=2(b+h)     (D)a=(b+h)
Y2+xy-12x2 =0 eq _  (1) and ax2+2hxy+bybe eq-2)
Let y=mx be the common line for eq 1 and 2 and now substitute y value in both equations and take x2 common
we get (m2-m+12=0) -(3)Roots of eq (3)are +3 and
-4 substitute in eq 2 we get 9b+6h+a=0 eq-4
option (A) is correct if u want u can substitute value of a in eq 4
Thanks.. give me reply if it help u..
 

Provide a better Answer & Earn Cool Goodies

star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments


Ask a Doubt

Get your questions answered by the expert for free