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Lesson 8: Writing algebraic expressions introduction

# Writing expressions with parentheses

In math, using parentheses helps follow the correct order of operations. When multiplying a number by the sum or difference of two terms, like 5 times (x-2) or 10 times (y+3), parentheses ensure the addition or subtraction happens first. This avoids confusion and ensures accurate results. Created by Sal Khan.

## Want to join the conversation?

• If in elementary they taught us that "X" stands for being multiplied, but now they are telling us that we are supposed to use "⋅" then why didn't they always just teach us to use the "⋅" symbol instead of "X".?
• Because in Algebra, if you use "X" as multiplication you will confuse "X" as a variable. Example: 13xx+1
Did you understand that Example? Nope! Because it looks like a mess. So in middle school Algebra, that's why we use the dot for multiplication instead of X.
Also in Elementary school, we were not doing Algebra.
• hello mr khan i like your website
• I shouldn't be in 8th grade and be doing 6th grade problems
• you should alwsys be looking to improve skills that you are "expected" to know
• Am I the only one who sees "`5` times the difference of `x` and `2`" as `5.|x-2|`?
Because "the difference of `x` and `2`" doesn't seem to show direction of subtraction, doesn't say are we subtracting 2 from x or x from 2, it just says "The difference between them". and the absolute value gives just that.
• There is a difference between 5(x-2) and 5*|x-2|. Try some points to see if they are the same thing. Let x=0. 5(0-2)=-10 and 5|0-2|=10, so they are clearly not the same. The breaking point would be 2. At 2, they are both 0. if x>2, they are the same. However, for x < 2, they diverge and absolute value gives the additive inverse of the correct answer.
• Written in English?! NoooOOoo..
I tHoUgHt It WaS wRiTtEn In JaPeNeSe!!
• I don't get the part about using the parentheses
• You have to think of somethings as quantities that go together. if you say difference of x and 2, you have to figure where the - sign goes, so it fills in for the and to get x-2. These go together, so you need the parentheses to show them as going together. If you have 5x-2, it would have to read 5 times x minus to or the difference of 5 times x and 2 (this is similar, but the x and 2 are not linked together in this case, thus the - sign still takes the place of amd, but no parentheses because they are not linked together. Does this help at all?