6. A drug is injected into the body in such way that the concentration, C. in the blood at time t hours is given by the function C(r)=10(e'2' 2'3' ). At what time does the highest concentration occur during the first 5 hours? 0 7. Determine the equation of the tangent to the graph of y = xcos 2x at x = E. 0 . . . . . . . sin: . 8. An object moves along a lme so that in t seconds 1ts posmon 15 $0) = 3 2 , where s [S + COS f . . . . .7!\" the dlsplacement in metres. Find the rate of change ofthe displacement at t = 1 seconds. [Remember your units.) 0