Straight line graphs

• What is the general form of a straight line equation?

  y = mx + c
• What does 'm' represent in the equation y = mx + c?

  'm' is the gradient of the line
• What does 'c' represent in the equation y = mx + c?

  'c' is the y-intercept of the line
• How do you find the y-intercept of a line from a graph?

  Locate where the line crosses the y-axis
• What is the formula to calculate the gradient of a line?

  Change in y divided by change in x
• How do you determine the change in y between two points?

  Subtract the y-values of the points
• How do you determine the change in x between two points?

  Subtract the x-values of the points
• What is the gradient if the change in y is -9 and the change in x is 3?

  -3
• What is the equation of the line if m = -3 and c = 2?

  y = -3x + 2
• What is the y-intercept of the second line discussed?

  -3
• How do you find the gradient for the second line?

  Calculate change in y divided by change in x
• If the change in y is 1 and the change in x is 4, what is the gradient?

  1/4
• What is the final equation of the second line if m = 1/4 and c = -3?

  y = 1/4x - 3
• What are the steps to find the equation of a line from a graph?

  1. Write y = mx + c
  2. Identify the y-intercept (c)
  3. Choose two points on the line
  4. Calculate change in y and change in x
  5. Compute the gradient (m)
  6. Substitute m and c into the equation
• What are the key components needed to write the equation of a line?

  • Gradient (m)
  • Y-intercept (c)
  • Equation format (y = mx + c)