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## 6th grade

### Course: 6th grade > Unit 6

Lesson 6: Expression value intuition# Expression value intuition

In an expression like 2x+7, the value of x can change. As the variable increases and decreases, what happens to the value of the expression?

### Make sure you understand the question that Sal solved.

## Let's try some practice problems!

## Want to join the conversation?

- I don't understand how any of this works.(5 votes)
- It's probably easier just to look at the equations rather than talk about it...

When you have 2x+7, when x is 1, the answer is 9. When x goes up to 2, the answer is 11. 11 is more than 9, so as the value of x increases, the value of the expression also increases.

But when the expression is something like 10-x, when x is 1, the answer is 9. When x is 2, the answer is 8. 8 is less than 9. So as the value of x increases, the value of the expression decreases in this case.

Hope that helps.(24 votes)

- there seems to be many quetions on this topic. let me clear up all your confusions. just fill in the problems above with a number like 1 and do it than fill it again with a number higher. if the answer u get is lower than the other one it decreases and if it is higher than it increases and if it is the same it is the last choice. i hope this helped u all. bye bye and feel free to ask any questions to me. i will gladly try to answer them. got it guys and girls(13 votes)
- I don't understand because when I was doing the math above one day I did that same kind of math and I picked increase and it was wrong then I picked decrease and it was wrong then I picked it stays the same and it was wrong I didn't understand why it didn't tell me which one was right.(9 votes)
- It was probably a mistake in the coding. I didn't have a problem with it. Try it again and see if it works!(3 votes)

- Can any of you guys can help me with this? I am really struggling with this topic. Please help...(8 votes)
- What part of it do you not understand? If it's all of it, you should probably go to previous lessons, and study a bit more. If there's a particular section you don't understand, or a part where it gets confusing, then we can better help you.(1 vote)

- Why does it stay the same? It would decrease because it's a division problem. How does it stay the same?(4 votes)
- 2t divided by t is the same as 2 - the t on top and bottom can 'cancel' each other out (as they'll grow at the same rate).

It's a tricky one and will become more apparent as you go further through the Algebra syllabus here!(4 votes)

- Hi guys, I just wanted to understand the goal of this particular lesson...

I am in no way trying to be cynical, but, serious

What's the point of this?

Do we memorise this?

i.e.

"When you are subtracting a variable that it is Increasing, the expression Decreases"

"When you are dividing by a variable that decreases but still remains a whole number, the expression Increases"

"When you are dividing an increasing variable by itself, as long as it is a whole number, regardless of the value of the Variable, the answer will always be the coefficient divided by the coefficient" - in which case the usage of the variable becomes obsolete.

Please explain,

Thank You(5 votes)- It gets you thinking about numbers, variables and their relationship. As you go further into the algebra playlist, it becomes apparent.(2 votes)

- This makes no logical sense. If k=1 then 1+35=36, If k=2 then 2+35=37. both numbers are increasing. Yet the right answer is that it decreases. The explanation isn't really an explanation but a string of numbers. How could these numbers be decreasing? The second expression of the exercise says it decreases also but yet the expression is now 30-3a. I find there's no pattern regardless if the expression is addition or subtraction.(3 votes)
- I believe you are getting confused. The question is asking what will happen to k or a when their values are changed. Number k’s value is decreasing, so the overall sum is going to get smaller. Number a is a little different though, because now we are increasing the value of the subtrahend (the number that is subtracting the minuend), so the value will decrease. The questions are a little confusing so you might need to understand what exactly the question is telling you.(2 votes)

- i still don"t understand the concept. Hope someone can help me simplify it to my understanding(3 votes)
- it hard but not that much(3 votes)
- The video says, and the table shows, that the last problem would stay the same, yet the system markd this response as incorrect. It says that 2(t/t) decreases. Does anyone know why?(3 votes)
- I just tried it. I selected "stays the same" and it was marked correct.(2 votes)