3 Calculus Questions, Multiple Choice... Please Help?

Question

3 Calculus Questions, Multiple Choice, Please Help, Pictures included! click links for problems...
I always give out best answer points

3 questions

Question 1

http://i106.photobucket.com/albums/m254/meskodaclown/calchelpmeeee1.gif



Question 2

http://i106.photobucket.com/albums/m254/meskodaclown/calchelpplease2.jpg



Question 3

http://i106.photobucket.com/albums/m254/meskodaclown/pplleaseehelp33.jpg


Thank you so much! Some details / explanations to the solutions would help me out a lot for my future test as well... Thanks..

Answer 1

1. c

2. b

3. b

the first two are obvious; you just look to see where the graph is the "HIGHEST" or "LOWEST" and see what the x value is for those points. A high point will indicate a maximum and vise-versa

For the third problem, you must take the derivative of the function:

you will get: 24x^2 + 42x -12
divide that by 6: 4x^2 + 7x - 2
when factored out: (4x - 1) * (x + 2)

so the critical points (points where max/mins exist) are:
x = 1/4 and x = -2

now find the second derivative: 48x + 42
plug your critical points into the second derivative, a positive value means concave up and a MINIMUM, a negative value means concave down and a MAXIMUM.

Answer 2

I don't have internet so I can't check out those links. Sorry.

Answer 3

Ans. 10 km/hr E Solution. We've, b = 4 km/hr W => -b = -4 km/hr W or, -b = 4 km/hr (-W) or, -b = 4 km/hr E Therefore, 2a - b = 6 km/hr E + 4 km/hr E or, 2a - b = 10 km/hr E.

Answer 4

c

b

b