College algebra word problem

Question

The assets of A of public pension funds (in trillions of dollars) can be approximated by the function A=0.249x^2-2.65x+17.5(6<X<11, where X=6 corresponds with the year 2006. Complete the following: what were the assets in 2007? What year before 2009 produced 12.24 trillion in assets?

Answer 1

To find the assets in 2007, evaluate A when x=7.

 

 

To find the year before 2009 that produced 12.24 trillion in assets, we set A=12.24, and solve for x.

 

12.24 = 0.249x² - 2.65x + 17.5

 

 

Subtract 12.24 on both sides of the equation.

 

0 = 0.249x² - 2.65x + 5.26

 

 

We have a quadratic equation.  Use the quadratic formula to solve for x:

 

x = (-b ± √(b² - 4ac)) / 2a

 

where:

a = 0.249

b = -2.65

c = 5.26

 

Plug in these values into the formula to solve for x.  You will have two solutions because of the plus/minus sign.

 

Pick the value of x that is between 6 and 9.