Differential Equations Question 103
Question: The differential equation of the family of curves $ y=a\cos (x+b) $ is
[MP PET 1993]
Options:
A) $ \frac{d^{2}y}{dx^{2}}-y=0 $
B) $ \frac{d^{2}y}{dx^{2}}+y=0 $
C) $ \frac{d^{2}y}{dx^{2}}+2y=0 $
D) None of these
Show Answer
Answer:
Correct Answer: B
Solution:
Given equation $ y=a\cos (x+b) $
Differentiate it w.r.t. x we get $ \frac{dy}{dx}=-a\sin (x+b) $
Again $ \frac{d^{2}y}{dx^{2}}=-a\cos (x+b)=-y $ or $ \frac{d^{2}y}{dx^{2}}+y=0 $ .
BETA
