Question

Mathematics with applications in the management, Natural, and Social Sciences Twelfth edition

Chapter 6: Systems of Linear Equations and Matrices

6.1 Exercises

19.) The number of baby boomers has been decreasing and the number of millennials has been increasing. Now Millenials have surpassed boomers in number. The following equations approximate the population y (in millions) of the given generation in year x, where x = 14 corresponds to the year 2014. (Data from: Pew Research Center.)

Boomers: 10x+13y = 1125 Millenials: -2x+7y = 495

solve this system of equations, and interpret your answer

Answer 1

Answer:

In 2015 the both populations were the same and from that year the population of millennials surpassed the population of boomers

Step-by-step explanation:

$\left \{ {{10x+13y = 1125} \atop {-2x+7y = 495}} \right.$

x=14

Boomer: 10(14)+13y=1125

               140+13y=1125

                       13y=1125-140

                       y= 985/13

                       y= 75.77 (75.77 millions of boomers in 2014)

Millenials: -2(14) +7y = 495

                  -28 +7y = 495

7y= 495+28

y= 523/7

y=74.71  (74.71 millios on millenials in 2014)

In 2014 the population of boombers were still greater than the population of millennials

The solution of the system of equations will give us the point where the populations were equalized, and from that point the population of boombers will be less than that of the millennials.

Boomers: 10x+13y = 1125

                 y= (-10x +1125)/13

Millenials: -2x+7y = 495

                 y= (2x+495)/7

We match both expressions of "y"

(-10x +1125)/13 =(2x+495)/7

cross multiply:

(-10x +1125)*7 =(2x+495)*13

-70x + 7875 = 26x + 6435

we group similar terms:

7875 -6435 = 26x+70x

1440 = 96x

x= 1440/96

x= 15

In 2015 the both populations were the same and from that year the population of millennials surpassed the population of boomers