But in high school, we can rely on two-point formula to determine the tangent equation of a function. The closer two points are to the tangent equation, the more accurate they are.

Two-point formula determines the equation, such as (X 1 Y 1) (X2 Y2).

K=(Y2-Y 1)/(X2-X 1)

Because the tangent equation is Y=KX+B

Substitute the value of k into the coordinate point of (X 1 Y 1) and find the value of b.