Answer:
r = - 2
Step-by-step explanation:
Calculate the slope m using the slope formula and equate to [tex]\frac{1}{7}[/tex]
m = [tex]\frac{y_{2}-y_{1} }{x_{2}-x_{1} }[/tex]
with (x₁, y₁ ) = (- 9, - 3) and (x₂, y₂ ) = (- 2, r)
m = [tex]\frac{r+3}{-2+9}[/tex] , that is
[tex]\frac{r+3}{7}[/tex] = [tex]\frac{1}{7}[/tex] ( cross- multiply )
7(r + 3) = 7 ( divide both sides by 7 )
r + 3 = 1 ( subtract 3 from both sides )
r = - 2
