(4 2 _ 9) a) What is the inside function? What is its derivative? b) Perform the integration using u-substitution. 2. Which functions are solutions to the differential equation y" y = 0? Choose all that apply and justify your answers. a) y = ex b) y : sin(x) c) y = cos(3x) d) y = e" 3. Determine the value, At, so that y = k cos(3x) + 4-sin(x) is a solution to the differential equation y" + y = 9 cos(2x)