Straight-line graphs 2

Methods

• Given one point and the gradient
  • Substitute the gradient for m in y=mx + c
  • Substitute the x-values and y-values given into the equation
  • Solve the equation to find c
  • Write out the equation
• Given two points
  • Draw a sketch showing the two points
  • Work out the gradient of the line using a triangle
  • Use method 1 and one of the points given to find the equation

Positive or negative

• If the line slops down then the gradient is negative

Examiners report

• Make sure you know how to find the equation of a line through two points
  • Draw a sketch of the line
  • Use a triangle to find the gradient
  • Substitute the gradient and the x and y-values of one of the points into y=mx+c
  • Solve your equation to find c