Estimate the number of cell phone subscribers in 2008. Round to the nearest tenth.

For this case we have an exponential function of the form:

Where,

A: initial number of subscribers

b: rate of change

x: number of years

Part A:

The equation modeling the problem is given by:

For the year 2008 we have x = 2.

Substituting values:

Part B:

For the year in which the company reaches 278 million we have

Thus, the company reaches 278 million in the year 2009.

Step-by-step explanation:

x= -3 and

step-by-step explanation:

to find the roots of a cubic, use division or factoring to find the factors then set equal to 0. as this is a difference of cubes, it factors into

where a is the cube root of .

here   this is 27 and the cube root of 27 is 3. so we write using the form:

.

set each factor to 0 and solve for x.

x-3=0

x=3

the quadratic expression does not factor and must be solved using the quadratic formula.

where a = 1, b=3, and c=9

this cubic has two complex roots.