Please help me with this. thank you.

7. (7 points) Find the derivative f(t) = -sech(2e!) 8. (7 points) Find the linearization of the function f(x) = VI +3 at a = 1 and use it to approximate the numbers v3.98 and v4.05. What can you tell me about these approximations?9. (7 points) Find the points on the curve y = o - 3x -9r + 5 where the tangent is horizontal. 10. (8 points) A particle moves according to a law of motion s(#) - 2/1 - 5143 + }t - 81, : 2 0, where t is measured in feet and s in feet. a) When is the particle at rest? Hint: Factor by grouping b) When is the particle speeding up? Hint: Quadratic formula\f13. (7 points) The volume of a growing spherical cell is V = gay , where the radius is given as 36 cm with a maximum error in measurement of 0.3 cm. Use differentials to estimate the maximum error, relative error and percentage error. 14. (8 points) Two cars start moving from the same point. One travels south at 60 mph and the other travels west at 25 mph. At what rate is the distance between the cars increasing two hours later