NDA2017MathematicsDifferential EquationsActual
What is the differential equation corresponding to y^2-2 a y+x^2=a^2 by eliminating a ?
Options
- A(x^2-2 y^2 ) p^2-4 p x y-x^2=0
- B(x^2-2 y^2 ) p^2-4 p x y-x^2=0
- C(x^2+2 y^2 ) p^2-4 p x y-x^2=0
- D(x^2+2 y^2 ) p^2-4 p x y+x^2=0 where p = dy dx
Correct answer
A. (x^2-2 y^2 ) p^2-4 p x y-x^2=0
Step-by-step solution
aligned & y^2-2 a y+x^2=a^2 & y^2-2(y)(a)+a^2+x^2=a^2+a^2 & (y-a)^2+x^2=2 a^2...(i) aligned Dift w.r.t x aligned & 2(y-a) y^1+2 x=0 & (y-a) p=-x & y-a= -x p ...(ii) & a=y+ x p ...(iii) aligned (i) ( -x p )^2+x^2=2 (y+ x p )^2 aligned & =2 ( ( py + x )^2 p 2 ) & x ^2+ p ^2 x ^2 p ^2 = 2 ( p ^2 y ^2+ x ^2+2 pxy ) p ^2 & x ^2+ p ^2 x ^2-2 p ^2 y ^2-2 x ^2-4 pxy =0 & ( x ^2-2 y ^2 ) p ^2-4 pxy - x ^2=0 aligned