0 = k a = ax+k x = x**2/2 +k x**n = x**n+1 / n+1 + k 1/x**2 = -1/x +k cos(x) = sin(x) + k sin(x) = cos(x) + k cos(wt+C) = 1/w sin(wt+C) +k sin(wt+C) = -1/w(wt+C) + k u'u**2 = u**3/3 + k u'u**n = u**n+1/n+1 + k u'/2sqrt(u) = sqrt(u) + k u/u**2 = -1/u + k u' cos(u) = sin(u) u' sin(u) = -cos(u)