COMEDK2023Morning ShiftMathematicsDifferential EquationsActual
The solution of the differential equation ( d y d x ) y= (x+y)+ (x-y) is
Options
- Ax=-2 y+C
- By=-2 x+C
- Cy=2 y+C
- Dx=-2 y+C
Correct answer
B. y=-2 x+C
Step-by-step solution
The given differential equation is dy dx y = (x+y) + (x-y) . Using the trigonometric identity (A+B) + (A-B) = 2 A B , the equation becomes: dy dx y = 2 x y . Rearranging the terms to separate the variables: y y dy = 2 x dx . This simplifies to: y ^2 y dy = 2 x dx . Integrating both sides: y ^2 y dy = 2 x dx . Let u = y , then du = - y dy . The integral becomes: -u⁻² du = 2 x dx . u⁻¹ = -2 x + C . Substituting back u = y : 1 y = -2 x + C . y = -2 x + C . Answer: y=-2 x+C