The slope of a line
Given two points through which a line passes A(x1,y1), B(x2,y2), the slope of the line can be calculated with the formula:
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]
We are given the point A(-4,-8) and the (incomplete) point B(?,1). Knowing the slope is m=2, we can calculate the missing value at point B. Let's call it x: B(x,1).
Substituting all the values in the formula of the slope, we get:
[tex]2=\frac{1-(-8)}{x-(-4)}=\frac{9}{x+4}[/tex]
Operating:
[tex]\begin{gathered} 2(x+4)=9 \\ 2x+8=9 \end{gathered}[/tex]
Solving for x:
[tex]\begin{gathered} 2x=9-8=1 \\ x=\frac{1}{2} \end{gathered}[/tex]
The missing value is 1/2, thus point B is B( 1/2 , 1 )
