Determine whether each of the equations in Problems 1 through 8 is exact. If it is exact, find the solution. 1. (2x + 3) + (2y − 2) y? = 0 2. (2x + 4y) + (2x − 2y) y? = 0 3. (3x2 − 2xy + 2) + (6y2 − x2 + 3) y? = 0 4. dy dx = −ax + by bx + cy 5. dy dx = −ax − by bx − cy 6.