Math 151 Quiz 7 Sp ’15
Print Name & Section______________________________
1. Assume that x>5 and solve for x if log 3 ( x  8 )  log 3 ( x  3 )  2  log 9 ( x  5 )
Hint: log 9 u  c log 3 u Find c.
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2. f ( x )  log 2 ( x  2 x  15 )
a) Find the domain of f ( x ).
b) Find f ' ( x ).
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3. A culture begins with a weight of 2g. It grows exponentially so that after 5 hours it weighs 8g.
a) Find a formula for the weight after t hours.
b) When will it weigh 50g? Give an exact answer.
c) What is the rate of growth at 7 hours?