$y = c_1 x^4 + c_2 x^{-1}$

$y = c_1 x^2 + c_2 x^{-2}$

$y = c_1 x^3 + c_2 x^{-2}$

$y = c_1 x^2 + c_2 x^{2} \ln(x)$