part (a)
use the substitution u = (y-x) to find the general family of solutions of the differential equation:
dy/dx = sin(y-x)
part (b)
show that if a new independant variable is defined by y = z^(1-n) then the differential equation:
dz/dx + p(x)z = q(x)z^n where (n not equal to 1)
becomes a linear differential equation in y(x)
part (c)
use part (b) to solve the initial value problem
xz dz/dx = x^2 + 3z^2 where z(1) = 1