Less Than

If x is zero, is the following true?

-7 < 3x + 2 < x + 2

In the back of your books write down at least 10 values of x which satisfy this inequality statement.

"<" means "is less than"


Topics: Starter | Algebra

  • Transum,
  • Monday, March 10, 2014
  • "This quite an advanced mathematical statement but sometimes it is effective for pupils to learn about a concept by unpicking a more complex problem rather than starting with the very simplest examples. A little 'trial and improvement' is expected though of course those with experience of solving inequalities may choose to solve the problem in the way the answer is presented below."

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Answers

When x is zero the statement is not true.
Here are ten values of x which make the statement true:
-2.85, -2.7, -2.55, -2.4, -2.25, -2.1, -1.95, -1.8, -1.65, -1.5,
there are of course many other values which make the statement true.

An inequality like this can be solved by splitting it into two parts:

-7 < 3x + 2
-9 < 3x
x > -3
3x + 2 < x + 2
2x < 0
x < 0

So the complete answer is -3 < x < 0

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Laptops In Lessons

Teacher, do your students have access to computers?
Do they have Laptops in Lessons or iPads?

Whether your students each have a TabletPC, a Surface or a Mac, this activity lends itself to eLearning (Engaged Learning).

Laptops In Lessons

Here is the URL for a concise version of this page without comments or answers.

Transum.org/go/?Start=May10

Here is the URL which will take them to a related student activity.

Transum.org/go/?to=Inequalities

Try Level 7

 




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