Question

If a point on a line is already known, what else is needed in order to create an equation?

Answer 1

Another point, so that you can calculate the gradient.

Answer 2

so two points?

Answer 3

Yes, but the answer is probably just "the gradient".

Answer 4

two more points a slope and a point
a slope two slopes

Answer 5

those are the choices

Answer 6

Stroodle is correct, 2 points determine a line.

OTOH, if Mr KindHeartedSoul is good enough to provide u with the slope (gradient) that will also do.