Line Graph Formulas

Question 1

Formula for Gradient of a Line?

Answer 1

m = Δy/Δx = (y2 − y1) / (x2 − x1)

Question 2

Midpoint of a line?

Answer 2

Midpoint = ( (x1 + x2) / 2 , (y1 + y2) / 2 )

Question 3

Distance between two points?

Answer 3

sqrt( (x2 − x1)^2 + (y2 − y1)^2 )

Question 4

Finding an Equation using Gradient and a Point?

Answer 4

y − y1 = m(x − x1)

Question 5

Horizontal and vertical lines?

Answer 5

Horizontal line: y = k (gradient = 0)
Vertical line: x = k (gradient undefined)

Question 6

Graph interpretation facts?

Answer 6

Positive gradient → line slopes up
Negative gradient → line slopes down
Zero gradient → horizontal line
Undefined gradient → vertical line

Question 7

Reading values from a line graph?

Answer 7

Interpolation = reading between points
Extrapolation = predicting beyond points