Comment on A - ( B x C ) + ( D x E ) = A - ( B x C ) - ( D x E ) if A > B + C + D + E
sxan@midwest.social 3 weeks agoI was trying to figure out how you came up with this - even given that you’re reh learning math - and thought “oh, maybe their native language is read right to left, so 1 + 1 = 2, and 10 - 2 = 8.” But then doing that you’d also go “1 - 1 = 0, and 10 - 0 = 0,” so I honestly don’t know how you’re getting there.
And then I thought, “maybe they think subtraction comes first”, but then (10 - 1) + 1 is 10, and (10 - 1) - 1 is 8.
I can’t think of any consistent rules that would produce this. You’d have to do:
- 10 - (1 + 1), and
- (10 - 1) - 1
I’m really curious about your thought process.
Incidentally, my wife was home schooled except her mother didn’t participate, so she never learned anything beyond basic addition and subtraction, and the single digit multiplication table. When she finally went for her GED she was in her 20’s, and we spent many, many hours together tutoring.
So, you’re getting a lot of negative reactions, but don’t let it get you down. Keep up with it; it’s valuable to learn.
BTW, my wife eventually graduated Summa Cum Laude in both her Bachelor’s and her Master’s degrees - non-STEM, so algebra was all she needed, but she fought hard for that 4.0, and she got it.
Arkouda@lemmy.ca 3 weeks ago
This is the back story of the silliness from another comment. I simply misremembered what to do and did addition before subtraction instead of left to right. I am still not sure exactly why because I literally just read a section on order of operations and my brain did the rest. I am usually not so bad at math, but my brain can be my worst enemy. haha
SmartmanApps@programming.dev 3 days ago
No, what you actually did was put it inside brackets, thus changing the number of terms. Doing addition first gives the exact same answer as doing subtraction first…
subtraction first 10-1+1=9+1=10
addition first 10+1-1=11-1=10
You did 10-(1+1), hence the wrong answer. It doesn’t matter which order you do it, though often students make mistakes with signs when they change the order, which is why we teach to do left to right.
Arkouda@lemmy.ca 2 days ago
The brackets are used to make the equation look cleaner, and the issue for declaring the statement true was doing Addition and Subtraction in the wrong order.
A - ( B x C ) + ( D x E ) = A - ( B x C ) - ( D x E )
Using your example:
10 - 1 + 1 = 10 doing the subtraction first. 10 - 1 + 1 = 8 doing the addition first.
When doing the other side of the equation:
10 - 1 - 1 = 8 regardless of order because it is all subtraction.
By doing it out of order and incorrectly I was able to make my statement true that as long as A was greater than the sum of B-E both sides would be equal.
SmartmanApps@programming.dev 2 days ago
No, they’re used to show deviations from the usual order of operations. If I want 2+3x4 to equal 20, then I have to write (2+3)x4.
No it isn’t. 10+1-1=11-1=10 is addition first. Note same answer, You did 10-(1+1) - you added brackets which changed the answer, thus a wrong answer
Not all of it. You’re forgetting the 10 is really +10. -10-1-1 would be all subtraction. +10-1-1 is addition and subtraction.
Yes it is! 😂 It is always the same regardless of order, as I have just shown you, again.
10-1+1=9+1=10
10+1-1=11-1=10
-1+1+10=0+10=10
1-1+10=0+10=10
1+10-1=11-1=10
-1+10+1=9+1=10
It’s NOT incorrect to do 10-1+1. It IS incorrect to do 10-(1+1), which is what you did
It was solely because you did it incorrectly. Order doesn’t change anything.
sxan@midwest.social 3 weeks ago
Ah. So you gave addition a higher precedence than subtraction. That makes sense.