Question

What is the equation in point-slope form of the line passing through (1, 9) and (−1, 11)?
y + 9 = −(x − 1)
y − 9 = 1(x + 1)
y + 9 = 1(x + 1)
y − 9 = −(x − 1)

Answer 1

y-y1 = m(x-x1)
m is the slope an you can use (y2-y1)/(x2-x1) to find the slope

Answer 2

understand?