JEE Main20199 Jan 2019Morning ShiftMathematicsDifferential EquationsActual
If y = y ( x ) is the solution of the differential equation, x d y d x + 2 y = x 2 satisfying y 1 = 1 , then y 1 2 is equal to
Options
- A7 64
- B1 4
- C13 16
- D49 16
Correct answer
D. 49 16
Step-by-step solution
Given differential equation can be written as d y d x + 2 y x = x , which is a linear differential equation. If = e ∫ 2 x d x = e 2   l n   x = x 2 Solution is y . x 2 = ∫ x . x 2 d x ⇒ y . x 2 = x 4 4 + c Since, given curve passes through 1 , 1 ⇒ c = 3 4 Hence, y x = x 2 4 + 3 4 x 2 . So, y 1 2 = 49 16 .