coordinate geometry

Question 1

how should the equation of a line be written

Answer 1

ax + by + c = 0 (where a, b, and c are integers)

Question 2

how to work out the equation of a line with gradient m which passes through point (a, b)

Answer 2

m(x - a) = (y - b)

Question 3

work out gradient of a line that passes through (x1, y1) and (x2, y2)

Answer 3

(y2 - y1) / (x2 - x1)