It can be helpful to classify a differential equation so that we can predict the techniques that might help us to find a function that solves the equation. Two classifications are the order of the equation -- (what is the highest number of derivatives involved) and whether or not the equation is linear. Linearity is important because the structure of the family of solutions to a linear equation is fairly simple. Linear equations can usually be solved completely and explicitly. Determine whether or not each equation is linear:1. (1+y²)(d²y/dt²) + t(dy/dt) + y = et2. t²(d²y/dt²) + t(dy/dt) + 2y = sin t3. (d³y/dt³) + t(dy/dt) + (cos2(t))y = t³4. y'' - y + y² = 0You have 10 choices to choose for each problem:a. 1st. order linear differential equationb. 2nd. order linear differential equationc. 3rd. order linear differential equationd. 4th. order linear differential equatione. 5th. order linear differential equationf. 1st. order non-linear differential equationg. 2nd. order non-linear differential equationh. 3rd. order non-linear differential equationi. 4th. order non-linear differential equationf. 5th. order non-linear differential equation