Random math help.. -Hijacked with calculus 3 question

[trinironnie]

-6^2+4/-2 we are getting -20 but the books answer is 16.

[Yugl]

This is what happens when you don't parenthesis.

(6^2) = 36
Apply the negative (-36)
Add four (-32)
Divide by negative 2 (16)

[Mina]

[12:55:52] solipsism: order of operations is hard man
[12:56:17] YUGL: where are my parenthesis
[12:56:27] The Blackrose: That's my thought.
[12:56:57] YUGL: but yeah screwy either way
[12:56:58] The Blackrose: It's only -20 if all of that is / 2
[12:57:03] solipsism: answrr should be -38 actually
[12:57:12] The Blackrose: Otherwise... It's definitely not 16.
[12:57:32] The Blackrose: Solip, what does squaring do to a negative number?
[12:57:39] YUGL: Oh OH
[12:57:43] YUGL: I see the 16
[12:57:45] YUGL: lol
[12:57:47] The Blackrose: ?
[12:57:58] YUGL: (6^2) = 36
[12:58:04] YUGL: then apply negative
[12:58:07] solipsism: yep
[12:58:08] YUGL: then add 4
[12:58:12] YUGL: divide by negative 2
[12:58:16] solipsism: wait what
[12:58:18] YUGL: woooow
[12:58:23] YUGL: no parenthesis hard
[12:58:24] The Blackrose: ... lolwut
[12:58:32] Mina: lol
[12:58:39] The Blackrose: Jesus, yeah, the lack of parenthesis is a killer.
[12:58:50] The Blackrose: That makes sense.
[12:59:05] Mina: Going to just copy this chat
[12:59:08] Mina: and paste in the thread
[12:59:15] solipsism: why are you adding 4 first
[12:59:45] YUGL: It's just one way to get 16
[12:59:51] YUGL: it's break order of operations
[12:59:53] YUGL: but it works
[12:59:56] The Blackrose: solip, he's assuming the expression is actually [-(6^2) + 4]/2
[13:00:01] solipsism: as it's written it;s -38
[13:00:05] The Blackrose: Well, -2
[13:00:09] YUGL: ^ TBR

[Ksandra]

Are you sure you wrote it right? I get 34, no idea how you get -20

(Also, are you American? I know people in other countries do things other than PEMDAS)

If American:

-6^2=36

4/-2 = -2

36 + -2 = 34

[edit] ya either you didn't write the parenthesis in, or the book didn't.

[solipsism]

If you copied this as it is in the book, then throw that book away cause it's shit.

[octopus]

https://www.google.com/#q=-6%5E2%2B4%2F-2

http://www.wolframalpha.com/input/?i=-6%5E2%2B4%2F-2

[The Blackrose]

tl;dr: Parenthesis are fucking important.

[Ksandra]

https://www.google.com/#q=-6%5E2%2B4%2F-2

Kinda wrong oddly enough. If you look, google auto puts in parenthesis.

-6^2 =/= -(6^2)

(first being what OP wrote, second being what google auto changed)

[edit] Ok I am wrong I guess now that defaults to -(6^2), is that because of typing or am I just old?

[Raldo]

In the book, was it perhaps written like this?

-6^2+4
-2

That makes all the difference, as it's clear the division is the last operation.

[Mina]

I don't know but none of you guys are allowed to edit and fix this shit because I love looking at everyone trying to math this out lol.

[Ksandra]

I don't know but none of you guys are allowed to edit and fix this shit because I love looking at everyone trying to math this out lol.

tl;dr: Parenthesis are fucking important.

^

I am actually curious about this.

I was always raised with the idea that if you see -6^2 it meant (-6)^2 not -(6^2). But that was back in the day of handwriting everything, and you didn't really do this stuff with typing. (I can't actually remember how calculators handled it back in the day.)

Perusing the internet and I see sites that say one way, and sites that say another.

So now I wonder if it got changed, my school textbooks were retarded, is it regional, etc.

[The Blackrose]

Google's calculator is the only time I have ever seen it treat -x^y as -(x^y) instead of (-x)^y.

Excel and a number of TIs I have used over the years have treated it as (-x)^y.

[Tajin]

Its still the same, that is: -6^2 == (-6)^2 =/= -(6^2)

[Yugl]

^

I am actually curious about this.

I was always raised with the idea that if you see -6^2 it meant (-6)^2 not -(6^2). But that was back in the day of handwriting everything, and you didn't really do this stuff with typing. (I can't actually remember how calculators handled it back in the day.)

Perusing the internet and I see sites that say one way, and sites that say another.

So now I wonder if it got changed, my school textbooks were retarded, is it regional, etc.

Depends on how layman your textbooks are (If they're written for children, they may have done that to simplify the expression). My TI calculator takes (-6^2) as (-36). It makes sense if you treat a unary as negative or subtraction since PEMDAS places exponents before multiplication/subtraction.

ex: (-6^2) = (-1)(6^2) = (-36) OR (-6^2) = (0)-(36) = (-36)

[Ksandra]

Depends on how layman your textbooks are (If they're written for children, they may have done that to simplify the expression).

I am talking about advanced algebra in middle school/hs, but we didn't use TI calculators until advanced trig/statistics in 10th grade.

Keep in mind this would have been, again, during the like green screen computer age, so TI calcs were more for graphing, and everything else was by hand.

[octopus]

lol I downloaded a TI graphing calculator emulator for kicks >_>

[Ksandra]

Just as a note, I firmly believe TI goes to your dumpsters in the middle of the night and steals all your claculators you tossed after HS. They then just rehash them and sell them for $100.


I mean seriously, how is this shit still that much money? Technology usually makes things cheaper. When I tutored kids at a hw club, their brand new TI's looked and functioned the same as the one I bought fucking 20 years ago.

[Yugl]

I am talking about advanced algebra in middle school/hs, but we didn't use TI calculators until advanced trig/statistics in 10th grade.

Keep in mind this would have been, again, during the like green screen computer age, so TI calcs were more for graphing, and everything else was by hand.

The convention varies by application, but the standard seems to be what I said.

[solipsism]

I don't understand why there is confusion on this. You do the exponent first then apply the negative, this is according to order of operations.

[BaneTheBrawler]

Just as a note, I firmly believe TI goes to your dumpsters in the middle of the night and steals all your claculators you tossed after HS. They then just rehash them and sell them for $100.


I mean seriously, how is this shit still that much money? Technology usually makes things cheaper. When I tutored kids at a hw club, their brand new TI's looked and functioned the same as the one I bought fucking 20 years ago.

capitalism