x²+y²-3x+λy-5=0.......................(1)
and 4(x²+y²)-12x-y-9=0
Or x²+y²-3x-y/4-9/4=0...................(2)
TO FIND:
Value of λ If circle (1) and (2) become concentric
SOLUTION:
The std equation of a circle is:
x²+y²+2gx+2fy+c=0...................(3)
centre is (-g,-f)
comparing (2) and (3) we get
g=-3/2 ,f=-1/8,c=-9/4
So centre of circle (2) is (-3/2,-1/8)
Now comparing (1) and (3) we get
g=-3/2,f=λ/2
So centre of circle (1) is (-3/2,λ/2)
Circle(1) and (2) become concentric if the centre of both the
circles is same
Thus the centre of circle (1) is (-3/2,-1/8)
On comparision we get
x coordinates are same
and y coordinate
λ/2=-1/8
λ=-2/8=-1/4
RESULT:
λ = -1/4