Q4: (T=5, C=2) Determine the values of x where the graph of each function has a horizontal tangent. i. y = (x-4)5 ii. y=(x-x)2 Q5: (K=4, C=2) For what values of a and b will the parabola y = x + ax + b be tangent to the curve y=x at point (1, 1)? Q6: (A=5, C=1) Sam applies the brakes steadily to stop his car, which is travelling at 20 m/s. The position of the car, s, in metres at 1 seconds, is given by s(t) = 20t - 0.31. Determine a. the stopping distance b. the stopping time c. the deceleration at 2 s Q7: (A=5, C=2) You are given a piece of sheet that is twice as long as it is wide and has an area of 800m. Find the dimensions of the rectangular box that would contain a maximum volume if it were constructed from this piece of metal by cutting out squares of equal area at all four corners and folding up the sides. The box will not have a lid. Give your answer correct to one decimal place.