9b 9a) Use the slope formula to determine the rate of change eq y- and find the y-intercept "5" by substituting the x and y values into y=mx + b

Respuesta :

A) We need to find the rate of change of the function first.

The rate of change or slope of the line is:

[tex]m=\frac{y_2-y_1}{x_2-x_1_{}}[/tex]

Where x and y are the coordinates of a point in line.

In order to calculate the slope we can take the poinst:

x1 = -6, y1 = 4

x2 = -2, y2= 1

Using the formula of above we find that the slope is:

[tex]m=\frac{1-4}{-2-(-6)}=-\frac{3}{4}[/tex]

Now, in order to find the value of y-intercept of the line we can use formula:

[tex]y=m\cdot x+b[/tex]

Which is the function of the line. From the formula of above we don't know the value of b (the y-intercept).

But we know that the formula must be valid for a point in the line. We can find the value of b replacing the coordinates of a point in the line, let's choose: x = -6 and y = 4, so:

[tex]4=\text{ m}\cdot(-6)+b[/tex]

Now we use the value of m of above:

[tex]4=(-\frac{3}{4})\cdot(-6)+b[/tex]

And from the last equation we can see that:

[tex]b=4-\frac{3}{4}\cdot6=4-\frac{9}{2}=\frac{8}{2}-\frac{9}{2}=-\frac{1}{2}[/tex]

So, the equation of the line is:

[tex]y\text{ = -}\frac{\text{3}}{4}\cdot x-\frac{1}{2}[/tex]

And the y-intercept is obtain replacing x = 0, so the y-intercept is: y = -1/2

b) From the stepts of above we already know an equation that represents the function! It is:

[tex]y\text{ = -}\frac{\text{3}}{4}\cdot x-\frac{1}{2}[/tex]

c) Now, we need to use the last equation to find y = n in the table. We know from the table that the value x for that value of y is x = 3, so we replace that value in the equation of the line:

[tex]y\text{ = -}\frac{\text{3}}{4}\cdot3-\frac{1}{2}=-\frac{9}{4}-\frac{1}{2}=-\frac{9}{4}-\frac{2}{4}=-\frac{11}{4}[/tex]

So the value of n is:

[tex]n\text{ = -}\frac{\text{11}}{4}[/tex]