In 2004, a magazine's circulation was about 1,000,000 readers. In 2014, the magazine had about 2,000,000 readers. Write a linear model that shows the number of readers, r, of the magazine t years after 2000.
r(t)=

Respuesta :

Answer:

[tex]r(t)=100,000t+600,000[/tex]

Step-by-step explanation:

Let

r ----> the number of readers (y-coordinate or dependent variable)

t ----> the number of years after 2000 (x-coordinate or independent variable)

Remember

2004 ----> represent t=4 years

2014 ----> represent t=14 years

we have the ordered pairs

(4,1,000,000) and (14,2,000,000)

step 1

Find the slope

The formula to calculate the slope between two points is equal to

[tex]m=\frac{y2-y1}{x2-x1}[/tex]

substitute the values

[tex]m=\frac{2,000,000-1,000,000}{14-4}[/tex]

[tex]m=\frac{1,000,000}{10}[/tex]

[tex]m=100,000\frac{readers}{year}[/tex]

step 2

Find the equation of the line in point slope form

[tex]r-r1=m(t-t1)[/tex]

we have

[tex]m=100,000\\point\ (4,1,000,000)[/tex]

substitute

[tex]r-1,000,000=100,000(t-4)[/tex]

step 3

Convert to slope intercept form

[tex]r=mt+b[/tex]

isolate the variable r

[tex]r-1,000,000=100,000t-400,000\\r=100,000t-400,000+1,000,000\\r=100,000t+600,000[/tex]

step 4

Convert to function notation

[tex]r(t)=100,000t+600,000[/tex]