Recognise and plot lines y = kx and y = −kx

Home learning focus

In this lesson you will explore straight line graphs that pass through the origin.

This lesson includes:

  • one slideshow
  • two interactive activities

Created in partnership with Pearson

Learn

Work through these slides. You will need to draw some graphs and tables. Using squared paper will make it easier - there may be some in your school Maths workbook.

A table can be used to set out the values of x and y for the equation y = 3x. To work out the y coordinate, multiply the x coordinate by 3.

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Lesson summary:

  • Graphs of the form y = kx or y = -kx are plotted as straight lines that pass through the origin (0, 0). k represents any number.
  • The greater the value of k, the steeper the graph.
  • Graphs of y = kx slope upwards. They have a positive gradient.
  • Graphs of y = -kx slope downwards. They have a negative gradient.

Practise

Activity 1

Recognise and plot lines y = kx and y = −kx

Have a go at the worksheet below from Pearson. Print it out or write your answers on paper.

Recognise and plot lines y = kx and y = −kx

Activity 2

Changes to a line

Try this activity from GeoGebra

Move the slider to change the gradient of the line in increments of 0.5, between -5 and +5 and note what changes and what stays the same.

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