1. Solve:  3^-x = 0.7
   
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2. Solve:  3^x = 9 ( ³\/3)
   
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3. Solve:  1.1^x = 2
   
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4. Solve:  x = log₇2
   
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5. The half-life of carbon-11 is 20 minutes. How long will it take for 800 grams of carbon-11 to decay to:
1. 640 grams
   
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2. 40 grams
   
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