Answer:
The value of r is -1
Step-by-step explanation:
The slope of a Line
Suppose a line passes through points A(x1,y1) and B(x2,y2). The slope can be calculated with the equation:
[tex]\displaystyle m=\frac{y_2-y_1}{x_2-x_1}[/tex]
The points are (1,2) and (-5,r), and the slope is 1/2, thus
[tex]\displaystyle \frac{r-2}{-5-1}=\frac{1}{2}[/tex]
Operating:
[tex]\displaystyle \frac{r-2}{-6}=\frac{1}{2}[/tex]
Multiplying by -6:
[tex]2(r-2)=-6[/tex]
Dividing by 2:
[tex]r-2=-3[/tex]
Add 2:
[tex]r=-3+2=-1[/tex]
[tex]\boxed{r=-1}[/tex]
The value of r is -1
