please answer 2,3,4

A particle moves on the hyperbola xy = 15 for time t 2 0 seconds. At a certain instant, x = 3 and - = 6. Which of the following is true about y at this instant? y= 5 a.) y is decreasing by 10 units per second. y is increasing by 10 units per second. dy = 3. =4+30=0 C y is decreasing by 5 unit per second. d. X . - 30 y is increasing by 5 unit per second. at + y dx dt -10 2) Let x and y be functions of time such that the sum of x and y is constant. Which of the following equations describes the relationship between the rate of change of x with respect to time and the rate of change of y with respect to time? a. dt dt b. dx _ dt dt C. dy dk dt dt at. where K is a function of t d. dx_ at at dy = K, where K is a function of t 3) An isosceles right triangle with legs of length s has area A = = $2. At the instant when s = 32 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? 4) A person whose height is 6 ft is walking away from the base of a streetlight along a straight path at a rate of 4 feet per second. If the height of the streetlight is 15 feet, what is the rate at which the person's shadow is lengthening