Answer:
Option A.
Step-by-step explanation:
Lindsay used two points (x1, y1) and (x2, y2) to find the equation of a line y = mx + b, that passes through the points.
First she used the definition of slope and determined the value as
\(m=\frac{(y_{2}-y_{1})}{(x_{2}-x_{1})}\)
Now the equation of line becomes
\(y=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}x + b\)
Since this line passes through a point (x1, y1) then the equation of the line will be
\(y_{1}=(\frac{y_{2}-y_{1}}{x_{2}-x_{1}})x_{1}+b\)
\(b=y_{1}-(\frac{y_{2}-y_{1}}{x_{2}-x_{1}})x_{1}\)
Therefore option A. will be the correct option.
