MATH 121 Lecture : MATH130_BOYLE-M_SPRING2015_0101_MID_SOL_1
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The domain is (6, ); i. e. , all real numbers greater than 6. The range (set of outputs) is ( , ), i. e. , all real numbers. (b) (3 pts) solve log2(x) = 3. 2log2(x) = 2 3 x = 1/8 (c) (6 pts) solve ex = exex+1 . Ex = exex+1 ex/2 = exex+1 ex/2 = e2x+1 x/2 = 2x + 1 x. Potassium-40, with a half-life of 1. 25 billion years, has been used by geochro- nologists trying to sort out the mass extinction of 250 million years ago. Let t have units of billions of years. Let t = 0 be the time 250 million (. 25 billion) years ago. Let y(t) be the amount of potassium-40 in the creature at time t. the fraction we need to compute is y(. 25)/y(0). y(t) = y(0)ekt y(t) = y(0)e( ln 2)(1/1. 25)t y(. 25) = y(0)e( ln 2)(1/1. 25)(. 25) y(. 25) y(0) Solution: 2 /3 (c) (3 pts) for the population model function.
