AI generatedAlgebraKS3 / GCSE

Writing a line equation from a graph

Writing a line equation from a graph.

  • For a non-vertical straight line, use .
  • The gradient is change in divided by change in . The intercept is the value when .
  • Substitute a known point to find missing constant. Show the same operation on both sides.

Example 1

Find the equation of the straight line.

Coordinate graph−4−3−2−11234−12−10−8−6−4−2240AB
Find the gradient from two points.Substitute the point into .Subtract the numerical term from both sides.Substitute and into .

Example 2

Find the equation of the straight line.

Coordinate graph−4−3−2−11234−10−8−6−4−220AB
Find the gradient from two points.Substitute the point into .Subtract the numerical term from both sides.Substitute and into .

Your turn

Question 1

Find the equation of the straight line.

Coordinate graph−4−3−2−11234−8−6−4−220AB
Check answer
Find the gradient from two points.Substitute the point into .Subtract the numerical term from both sides.Substitute and into .
Question 2

Find the equation of the straight line.

Coordinate graph−4−3−2−11234−6−4−220AB
Check answer
Find the gradient from two points.Substitute the point into .Subtract the numerical term from both sides.Substitute and into .
Question 3

Find the equation of the straight line.

Coordinate graph−4−3−2−11234−8−6−4−220AB
Check answer
Find the gradient from two points.Substitute the point into .Subtract the numerical term from both sides.Substitute and into .
Question 4

Find the equation of the straight line.

Coordinate graph−4−3−2−11234−10−8−6−4−220AB
Check answer
Find the gradient from two points.Substitute the point into .Subtract the numerical term from both sides.Substitute and into .
Question 5

Find the equation of the straight line.

Coordinate graph−4−3−2−11234−12−10−8−6−4−2240AB
Check answer
Find the gradient from two points.Substitute the point into .Subtract the numerical term from both sides.Substitute and into .
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