equalities and inequalities help!!!?

You have 2 points for a graph; (1990,120.5) and (2000,140.5)

The instructions tell you to use the origin as 1990

x=0 therefore corresponds to (0,120.5) and (2000,140.5) would be the

same as (10,140.5)

Let's find the equation for the line that joins the 2 points.

The equation will take the form y=mx+b, where m is the slope of the line and b is the y-intercept..

Slope = m= rise/run, =(y2-y1) / (x2-x1)

m= 140.5-120.5 / 10-0

=20/10

=2

So y=2x+b

Pick either of the 2 given points to use in finding b. I'll use (0,120.5)

y=2x+b

120.5=2(0)+b

120.5=b

Our equation is now fully known . It is y=2x+120.5

Now, let's find the required estimated values.

At 1997, x=7 (since 1990 occured at x=0, 1997 is 7 away from 0).

y=2(7))+120.5

y14+120.5

y=134.5

At 2003, x=2003-1990, =13

y=2(13)+120.5

y=26+120.5

y=146.5

1997, 134.5 sales, in thousands

2003, 146.5 sales, in thousands

The Distance Formula is simply the Pythagorean formula, nothing more.

D^2= (y2-y1)^2+x2-x1)^2

D^2= (146.5-134.5)^2 +(2003-1997)^2

D^2=12^2+6^2

D^2=144+36

D^2=180

D= 13.42 units

Subtracting the 2 estimated values is y2-y1

=146.5-134.5

=12 units

The difference between the 2 answers is due to the fact that the

Distance Formula measures the length of the hypotenuse of the

triangle formed by the 2 given points, whereas the subtraction of the

2 y values measures one side of the right triangle.

The subtraction method is correct, since it calculates the change in

sales for 6 years, The Distance formula does not.