Question

Graph the line formed by the points (9,7) and (-9,1) Identify the slope (m):And Y-intercept (b): Write the slope-intercept equation of the line (y=mx+b):

Answer 1

In order to find the parameters m (slope) and b (y-intercept) of the equation y=mx+b, we need to apply the two points given, that is, we use the x and y coordinates in the equation.

Using the point (9,7), we have that:

$7=m\cdot9+b$

Using the point (-9,1), we have:

$1=m\cdot(-9)+b$

If we add both equations, we have:

$\begin{gathered} 7+1=9m-9m+b+b \\ 8=2b \\ b=4 \end{gathered}$

Now, finding the value of m, we have:

$\begin{gathered} 7=9m+b \\ 9m+4=7 \\ 9m=3 \\ m=\frac{3}{9}=\frac{1}{3} \end{gathered}$

So the equation of the line is y = 1/3 x + 4