Please answer all questions and show work so I can understand.

9) A radioactive material is known to decay at a yearly rate In proportional to the amount at each moment. There were 1000 10- In (1000/980) grams of the material 10 years ago. There are 980 grams 105 right now. What will be the amount of the material right after O 980 20 years? 9803 O 105 9803 O 103 10) Express the following equation of a circle in polar O p = 6 cos 0 + 8 sin 0 coordinates: O r = 3 cos 0 + 4 sin 6 (x - 3)- + (y -4)2=52 O y = 8 cos 0 + 6 sin 0 Or=5 11) Given x = 41 - 5 and y = f-, find dvdx at the point (x, y) at 0 2 which f = 2. 0 4 01 O 1/2 12) Which of the following points are not petal endpoints of r = O (r. 0) = (2, 0) 2 cos (40)? O (T, # ) = (2, 2 ) O (r, 0 ) = (-2, 4) O (r, 0 ) = 2, 3