Question 10625
Y = (1+x)^(-1)

dy/dx = (-1)(1+x)^(-2)

d2y/dx2 = (-1)(-2)(1+x)^(-3) = (-2)[((-1)(1+x)^(-2)](1+x)^(-1)
 
d2y/dx2 = (-2)dy/dx [(1+x)^(-1)]

(1+x)d2y/dx2 = -2dy/dx

(1+x)d2y/dx2 + 2dy/dx = 0