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## Pre-algebra

### Course: Pre-algebra > Unit 6

Lesson 4: 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.(12 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.(30 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(15 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.(11 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...(10 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.(3 votes)

- Why does it stay the same? It would decrease because it's a division problem. How does it stay the same?(5 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!(6 votes)

- why does it decrease if your added k + 35 as k decreases?(5 votes)
- Remember "death to the world?" and also it is because you are adding less to 35. Ex. if k = 5 k+35=40, but if k decreases (4) 35+4=39, so it decreased by 1.(5 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(6 votes)- It gets you thinking about numbers, variables and their relationship. As you go further into the algebra playlist, it becomes apparent.(2 votes)

- why are all theses comments so old!?(3 votes)
- Fr bro like some be from 8 years ago(3 votes)

- how do u use
**emojis**?(4 votes) - whats 93 times x if x is 63?(2 votes)
- Hi, Aroustahn!

Here it is, step by step (it might help to write it all down):

1. 3 times 3. Write down the answer under the threes.

2. 9 times 3. Write down the answer under the six and the nine.

3. Now write a zero under the answer from step one.

4. 6 times 3. Write the answer under the answer to step two. (You'll have to "carry" a number.)

5. 6 times 9 plus the number you "carried". Write the answer to the left of the answer from step four.

6. Add the answers together. Consider all the answers next to each other as one number.

You have your answer! For a more detailed (and probably easier to understand) explanation on how to multiply two digit numbers, go to this link (You'll have to type it into google. I*still*cannot figure out how to add a link correctly.):

https://www.khanacademy.org › cc-fourth-grade-math

(It should be the first video you see.)

Hope this helped! Have a good day!!(5 votes)