Consider the following system of equations: x + x = u- +y = x. (a) (2 points) Eliminate x and form a single ODE, written in standard form (i.e., output terms to the left and input terms to the right), with y as the output variable and u as the exogenous input. (b) (2 points) Eliminate y and form a single ODE, written in standard form (i.e., output terms to the left and input terms to the right), with x as the output variable and u as the exogenous input. (c) (4 points) Choosing states = x, x = y, and x3 = y, find the state-space (state-variable) representa- tion. Specifically identify the state variable functions f1, f2, and f3.