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# Expression value intuition

Explore how the values of algebraic expressions like 100-x, 5/x + 5, and (3y)/(2y) change as the values of the variables change.

## Want to join the conversation?

• so now the problem decreses? im confused
• If x increases, then 100-x decreases. For example, say that x=10. That means 100-x=90. If x=20, then 100-x=80. If x=30, then 100-x=70, and so on. If you have a constant first number in a subtraction problem, then the answer will get bigger as the second number gets smaller, and vise versa.
• For everyone who is confused:
If x increases, then 100-x decreases. For example, say that x=10. That means 100-x=90. If x=20, then 100-x=80. If x=30, then 100-x=70, and so on. If you have a constant first number in a subtraction problem, then the answer will get bigger as the second number gets smaller, and vise versa.
• The last problem i am having a little bit of trouble understanding why the value would stay the same.
• You have the fraction 3y/2y and you’re trying to figure out what will happen if y increases, assuming that y is a number greater than 0. Since any non-zero number divided by itself is equal to 1, we know that no matter what the value of y is, y/y is equal to 1. And any number multiplied by 1 stays the same, so the value of 3y/2y isn’t going to change.
• would it be different answers if the numbers were negative?
• Yes... even one different sign will generally create a different result
• Can someone give me formula for this?
Thank you
(1 vote)
• The point of this lesson is not a formula; not everything in math is a formula. The point of this lesson is improving your number sense, your understanding of effects of math operations, and your overall mathematical intuition. Usually, the difference between strong and average math students is that strong students have a more developed and more accurate intuition.

Accurate mathematical intuition is important on some types of college entrance exam math questions, especially quantitative comparison questions.
• I'm still pretty confused...
• what do you need help with zippyding6
• At why is x being increased? Shouldn't it be less so you can subtract without having it be a negative?
• what is the point how does it help us in later life?