Lesson video

Hi everyone, I'm Mr. Lund, and in this lesson we're going to be solving inequalities with unknowns on both sides of the inequality.

I want to start this lesson by recapping collecting like terms. Here is a bar model that represents an inequality.

Here are three number cards with three different inequalities.

Which of the number cards represents the bar model? Do you see by collecting all our like terms, I can say that 3t is more than t plus eight.

So practise the skill of collecting like terms. Pause the video and return and check your answers.

Here's the solutions to questions one and two.

Now strictly speaking in question one, here we have it.

It was true, we should really use this symbol, which is called the identity symbol.

It means that both sides are identical.

I've used an equal sign because some people aren't familiar with this, but strictly speaking, we should use an identity symbol.

You can solve inequalities in much the same way you would solve equations.

By subtracting a from both sides of this inequality, I can find that a subtract one is greater than zero.

One more step, I'm adding one to both sides, finds that a is greater than one.

I've solved my inequality.

I could even represent that on a number line.

Here is a different inequality.

By subtracting a from both sides, I find that 3a subtract one is greater than five.

Add one to both sides and I have my variable on one side and the six on the other.

Divide both sides by three, finds the solution that a is greater than two.

Pause the video here and come back to check your answers.

Here's the solutions to questions three and four.

In questions four a and b, you first have to collect your like terms before going on to solving those inequalities.

Here's questions five and six.

Pause the video and return once you have finished to check your answers.

Here's the solutions to questions five and six.

Now there's a lot more shuffling around of your inequalities, moving variables from one side to the other, moving numbers from one side to the other.

Take your time with them and try and write out each individual step that you're taking.

It can help you in exams to find the right answer.

when you are under pressure.

Well done for getting this far.

You can have a sticker from me.

Here we go, questions seven and eight.

Pause the video, return to check your answers.

Here's the solutions to questions seven and eight.

Well done for getting this far.

Hopefully you recognised the mistake that was modelled in that example.

And question eight you had to solve to find that y was greater or equal to negative one.

and then you could represent that on the number line.

I'm going to get back to my book.

See you in a bit.