Solve the initial value problem yy' +r = Vx? + y? with y(3) = 4. a. To solve this, we should use the substitution |help (formulas) help (formulas) Enter derivatives using prime notation (e.g., you would enter y' for ). U = u' b. After the substitution from the previous part, we obtain the following linear differential equation in x, u, u'. | help (equations). c. The solution to the original initial value problem is described by the following equation in r, y. | help (equations)