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Year 10 - Maths

Parallel linear graphs

Linear graphs

Unit Summary

In this unit pupils consider equations that produce parallel or perpendicular graphs and how their equations relate to each other.

Lesson Summary

You will learn to identify, from their equations or graphs, whether two lines are parallel.

Key Notes

  • Two lines are parallel if they are equidistant and never touch.
  • For linear graphs, the rate of change is constant.
  • If the gradients are the same then the linear graphs may be parallel.
  • The y-intercepts must be different, otherwise the lines are the same.

Vocabulary To Learn

  • Gradient: The gradient is a measure of how steep a line is. It is calculated by finding the rate of change in the y-direction with respect to the positive x-direction.
  • Intercept: An intercept is the coordinate where a line or curve meets a given axis.
  • Parallel: Two lines are parallel if they are straight lines that are always the same (non-zero) distance apart.

Common Mistakes To Avoid

  • Lines are parallel if they have the same gradient.

3 Quick Questions (With Answers)

1. Solve this in steps: explain the method from this lesson and why each step matters.

Two lines are parallel if they are equidistant and never touch. For linear graphs, the rate of change is constant.

2. Use this key word in a maths sentence and explain it clearly. 'Gradient'

The gradient is a measure of how steep a line is. It is calculated by finding the rate of change in the y-direction with respect to the positive x-direction. Use this word when showing your method, then check your final answer is reasonable.

3. Spot and fix this common maths mistake.

Mistake: Lines are parallel if they have the same gradient. Correction: Lines are parallel if they have the same gradient and different y-intercepts. Two lines are parallel if they are straight lines that are always the same non-zero distance apart.

More Lessons In This Unit

Browse all guides in the Year 10 Maths guide library.