please help solve 28-30

28. An isosceles right triangle with legs of length s has area Am At the bisloans when s - V32 centimeters, the area of the triangle is increasing at a rate of 12 square centimeters per second. At what rate is the length of the hypotenuse of the triangle increasing, in centimeters per second, at that instant? (A) (13) V32 (C) 18 (D) 3 Start of Applications of the Derivative Retest 29. Let f be the function defined by f (x) =x -3x2 -9x+11. At which of the following values of x does f attain a local maximum? (A) -1 (B) 3 (C) -3 (D) 1 30. The function of f is not continuous at x = 5. Which of the following statements must be false? (A) f (5) is undefined (B) lim f ( x ) - f (5 ) exists x-5 (C) lim f (x) does not exist (D) lim f (x) * f