21. Randy owns a computer store. In 1990, he sold 150 monitors. In 2000, he sold 900
monitors. Let x represent the number of years since 1990. Write a linear equation, in
slope-intercept form, that represents this data.

Answer :

Answer:

[tex]y=75x+150[/tex]

Step-by-step explanation:

Let [tex]y[/tex] represent the number of monitors sold.

Given:

[tex]x[/tex] is the number of years since 1990.

So, for the year 1990, [tex]x=0[/tex].

For the year 2000, 10 years passed. So, [tex]x=10[/tex].

Now, monitors sold in 1990 are 150. So, at [tex]x=0,y=150[/tex]

Monitors sold in 2000 are 900. So, at [tex]x=10,y=900[/tex]

Thus, the two points are [tex](0,150)[/tex] and [tex](10,900)[/tex].

The slope of a line with points [tex](x_{1},y_{1})[/tex] and [tex](x_{2},y_{2})[/tex]  is given as:

Slope, [tex]m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}[/tex]

For the points [tex](0,150)[/tex] and [tex](10,900)[/tex], the slope is given as:

Slope, [tex]m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}\\ m=\frac{900-150}{10-0}\\ m=75[/tex]

Now, the y-intercept is the point where [tex]x=0[/tex]. So, the point [tex](0,150)[/tex] has [tex]x[/tex] value as 0.

So, the y-intercept is 150.

Equation of a line in slope-intercept form is given as:

[tex]y=mx+b[/tex]

Where, [tex]m[/tex] is the slope and [tex]b[/tex] is the y intercept.

Here, [tex]m=75[/tex] and [tex]b=150[/tex].

Therefore, the equation that represents the above data is given as:

[tex]y=75x+150[/tex]

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