The population of a city has been growing according to the rate , where is the population in millions, and is the number of years. What was the population 2 years ago?
Since represents the number of years, substitute for the value of in the equation to find the population (in millions) 2 years ago.
Remember that a number raised to a negative power is equal to the reciprocal of that number raised to the positive value of the power.
So, 2 years ago the population was 10.88 million.