Exponential Function Vocabulary

What is it about the equation y = 2(9/7)^x that indicates that it is a model for exponential growth?

• The equation is growth because 2 is positive.

• The equation is growth because the factor is positive.

• The equation is growth because the factor is greater than one.

• The equation is growth because the exponent is always positive.

Consider the equation y=200(1.08)^x which models the increase in value of an autographed Annie program. Let y = the value of the item, let x = the number of years since the performance. What does the 1.08 in the equation indicate?

• The value of the item is increasing by $1.08 each year.

• The value of the item is increasing by 1.08% each year.

• The value of the item will increase to $200 1.08 years after purchase.

• The value of the item is increasing by 8% each year.

If you were asked to write an exponential function with an asymptote of y = - 2, what must you include in your equation?

• Subtract 2 from any exponential expression. Ex. y = (4)^x - 2

• Add 2 to any exponential expression. Ex. y = (4)^x + 2

• Raise the expression to the power of -2. Ex. y = x ^-2

• Subtract .02 from 1 to get a decay factor. Ex. y = (1 - .02)^x

A population of mutant venus fly trap plants are taking over an island in the South Pacific, capturing everything from insects to small rodents. When they were first discovered they covered 4 square kilometers. As the population grows, the plants spread and cover more land. Use the table to write an equation.

• y=4(4)^x

• y=4(2.68)^x

• y=4(1+1.67)^x

• y=4(1.67)^x

A population of mutant venus fly trap plants are taking over an island in the South Pacific, capturing everything from insects to small rodents. When they were first discovered they covered 4 square kilometers. As the population grows, the plants spread and cover more land. How many years will it take for the plants to occupy 400 km²?

• 8 years

• 9 years

• 10 years

• 11 years

This graph models y = (0.2)^x - 3. Which statement describes what happens to the y value as x increases?

• As the value of x becomes very large, the value of y approaches - 0.2.

• As the value of x becomes very large, the value of y approaches -3.

• As the value of x becomes very large, the value of y approaches -2.

• As the value of x becomes very large, the value of y will gradually

  decrease to negative infinity.

Consider the equation 70(0.8)^x + 2. What is the end behavior of the function as x approaches infinity?

• 
• 
• 
• 

You are sick and your doctor prescribes a medication. One dose is 200 mg. Every half hour 30% of the medication leaves the body. You take the first dose at 6 am. If y = amount of medication in the body and x = a 30 minute interval, what equation fits the scenario?

• y=30(0.70)^x

• y=200(0.30)^x

• y=200(x)^0.3

• y=200(0.70)^x

What parts of an exponential equation could you find in a table?

• The factor is found as the first difference in the table, and the value of a is where y=0.

• The factor is found as the common ratio in the table, and the value of a is where y = 0.

• The factor is found as the common ratio in the table, and the value of a is where y = 0.

• The factor is found as the first difference in the table, and the value of a is where x=0.

Is the pictured graph growth, decay, or linear or none?  

• Growth

• Decay

• Linear

• None