Generate an expression for the appropriate state function, if possible, for each of the following differentials (your results may include some unknown constants): dr - dy c) dF = -y dr +x dy + z dz d) dU = b) dw * da + dy y dr + x dy + zdz ) dw 3 %3D For a) and b), if a state function cannot be generated, determine the integrating denominator required to make dw an exact differential (after doing so, you do not need to determine the corresponding state function).