298 Higher Engineering Mathematics
- Evaluatef′′(θ )whenθ=0given
f(θ )=2sec3θ. [18] - Show that the differential equation
d^2 y
dx^2
− 4
dy
dx
+ 4 y=0 is satisfied
wheny=xe^2 x.
- Show that, if P and Q are constants and
y=Pcos(lnt)+Qsin(lnt), then
t^2
d^2 y
dt^2
+t
dy
dt
+y= 0