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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?
Expression value intuitionSee video transcript

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

What happens to the value of the expression 100, minus, x as x increases?

## Let's try some practice problems!

Question 1
• Current
What happens to the value of the expression k, plus, 35 as k decreases?

## Want to join the conversation?

• I don't understand how any of this works.
• 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.
• 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
• 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.
• It was probably a mistake in the coding. I didn't have a problem with it. Try it again and see if it works!
• Can any of you guys can help me with this? I am really struggling with this topic. Please help...
• 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?
• 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!
• 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.

Thank You
• It gets you thinking about numbers, variables and their relationship. As you go further into the algebra playlist, it becomes apparent.