Equation of a common tangent to `x^(2)+y^(2)=16" and "9x^(2)+25y^(2)=225` is :

Options

A. `3x+2y=5`
B. `sqrt(7x)+3y=16`
C. `x+sqrt(7)y=6`
D. `sqrt(7)x-sqrt(11)y=2`

Answer

B

Explanation

`{:(because,a.b.c" are in A.P.",implies,a+c=2b,implies,1+(c)/(a)-(2b)/(a)=0),(implies,1+alphabeta+2(alpha+beta)=0,implies,1+99+2(alpha+beta)=0,implies,alpha+beta=-50):}`