Question
A research lab grows a type of bacterium in culture in a circular region. The radius of the circle, measured in centimeters, is given by
- A research lab grows a type of bacterium in culture in a circular region. The radius of the circle, measured in centimeters, is given by r(t)=5-6/(t^2+3) where t is time measured in hours passed since a circle of a 1cm radius of the bacterium was put into the culture. Express the area, A(t), of the bacteria as a function of time, and find the approximate area of the bacterial culture in 4 hours.
- A(t) =(56/(t2+3))andtheareaafter4hours=14.72cm2
- A(t) = 2(56/(t2+3))andtheareaafter4hours=29.43cm2
- A(t) =(56/(t2+3))2andtheareaafter4hours=68.93cm2
- A(t) =(56/(t2+3))2andtheareaafter4hours=137.86cm2
2. A minivan was purchased for $32,000. If the value of the minivan depreciates by $1,700 per year find a linear function that models the value V of the car after t years. Use the function and find the value of the car after 5 years
- V(t) = -1,700 + 32000; value after 5 years = $23,500
- V(t) = -1,700 + 32000; value after 5 years = $30,000
- V(t) = -1,700 + 32000; value after 5 years = $33,700
- V(t) = -1,700 + 32000; value after 5 years = $40,500
3. A Pendulum moving in simple harmonic motion is modeled by the function s(t)=5cos(/4) where s is measured in inches and t is measured in seconds. Determine the first time when the distance move is 4 inches.
- .82s
- 2.6s
- 3.2s
- 9.9s
4. Solve2log5(x)log5(6x1)=0
- x = 1/6
- x = 1/5
- x = 5
- x = 6
5. Estimate the slope of the tangent line tof(x)=x3 at x=2 by finding the slope of the secant line through (2, f(2)) and (2.001, f(2.001)).
- 0.012
- 4.02
- 12.000
- 16.0
6. Use the Squeeze theorem to evaluate limx0f(x) where f(x) =x2cos(3/x)
- 0
- 1
7. Find the intervals over which the function f(x)=2x2+3x+1/x25x
- (,5)and5,)
- (,0)and(0,)
- (,0),(0,5)and(5,)
- (,5),(5,0)and(0,)
8. find a non-zero value for the constant k that makes the function f(x)={tankx/x5x+3x<0x0}continuous at x = 0
- -1/3
- 1/3
- 3
- -3
9. A store determines the daily profit on pens. Obtained by charging s dollars per pen P(s)=10s2+75s5. If the store currently charges 50 cents for a pen. Find the rate of change of profits.
- $30
- $60
- $65
- $85
10. A ball is dropped from the top of a building that is 15m high. The position of the ball after t seconds is given by the equation s(t)=4.9t2+15. Find the instantaneous acceleration of the ball after t seconds.
- 4.9m/s2
- 9.8m/s2
- 9.8tm/s2
- 4.9tm/s2
11 Findd/dx(3/x2)+x(x1)
- (3/x2)+2x1
- (6/x3)+1
- (3/x2)+1
- (6/x3)+2x+1
12. The price p (in dollars) and the demand x for an item is given by the price-demand function p(x) = 15-0.0015x. Find the marginal revenue at x = 1,000.
- $1.50
- $12.00
- $13.50
- $15.00
13. A bag of sand hanging from a vertical spring is in simple harmonic motion as given by the position function s(t)=sin((/2)t+/6)where t is measured in seconds and s is in inches. Find the velocity of the spring at t = 2 s..
- 3x/4
- /4
- 3x/4
- /2
14 Find dy/dx ify=tan1(x3)
- 1/1+x3
- 1/2x3(1+x3)
- 3x2/(1+x3)
- 3x/2(1+x3)
15. The volume of a right cylinder of radius x and height y is given by v=x2y. Suppose that the volume of the cylinder is constant at 250cm3. find dy/dx when x = 5 and y = 10
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