On a piano, the formula to determine the frequency of any pitch relative to the A above middle C (A440) is given by the expression , where x represents the the number of half-steps above or below A440. Which of the following is equivalent to ?





A scientist has 50 grams of a radioactive element. The amount of radioactive element remaining after t days can be determined using the equation . After two days the scientist receives a second shipment of 50 grams of the same element. The equation used to represent the amount of shipment 2 remaining after t days is . Which of the following is an equivalent form of the expression for the amount remaining in shipment 2?





An antibiotic kills 60% of bacteria in a sample of 100,000 each day. The equation represents the population, p1, after d days. Four days after introducing the antibiotic to the first sample, a scientist introduces the same antibiotic to a second population, p2. The number of bacteria after d days in the second population is represented by the equation . Which equation is equivalent to p2?





Which of the following is equivalent to ?





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