$().(1)\frac{d^{2}y}{d{x}^2}-4\frac{dy}{dx}-y=0$

$(2)y^{\text{'}\text{'}}-6y^{\text{'}}+10y=0$

$(3)y^{\text{'}\text{'}}-6y^{\text{'}}+9y=0$

$(4)y^{\text{'}\text{'}}+3y^{\text{'}}+2y=0$

Second order linear $($ODE$)$ with constant coefficient Homogeneous