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#81 - aliethecakeis
Reply +3
(07/13/2013) [-]
Could also be -2
#203 to #81 - aliethecakeis
Reply 0
(07/14/2013) [-]
I enjoy when my comments spark debates about math.
#107 to #81 - pebar
Reply +4
(07/13/2013) [-]
actually it's not
if x²=4, then x could be -2
but the function itself cannot be negative
#110 to #107 - articulate
Reply 0
(07/13/2013) [-]
This. caret.
#117 to #108 - cormy
Reply 0
(07/13/2013) [-]
I'm confused, where in your back up did it state that the function itself could not be negative? It said it COULD be, but we disregard it for the sake of simplicity.
#118 to #117 - pebar
Reply 0
(07/13/2013) [-]
It said it could be DEFINED as such, but it is not currently because that wouldn't be as simple.
A function by definition cannot produce multiple outcomes so the range is restricted.
#210 to #118 - demandred
Reply 0
(07/17/2013) [-]
f(x)=sqrt(x) is (in this case) a function that takes on the positive value of the sqrt of x. This bechause what you said, for a given x, f(x) can only have one value, so we forget about the negative one. It's still a solution to f(x) tho.
#163 to #118 - AeroChic
Reply 0
(07/13/2013) [-]
I'm also confused. Since this picture is not stating whether it's a function or not, wouldn't the negative still be considered?
#176 to #163 - pebar
Reply 0
(07/13/2013) [-]
this should explain it better

Every positive real number has two square roots, one positive and one negative. For example, the two square roots of 25 are 5 and −5. The positive square root is also known as the principal square root, and is denoted with a radical sign.

en.wikipedia.org/wiki/Nth_root#Square_roots
#165 to #163 - pebar
Reply 0
(07/13/2013) [-]
No.
The radical sign is itself a function (the f(x)= means it's a function too). If you want to include the negative half, you have to write it like so.

#211 to #165 - demandred
Reply 0
(07/17/2013) [-]
plus/minus sign indicates two solutions. The square root of a number has two real solutions. What you wrote has therefore 2*2=4 solutions, it's just that (in the case of x=4) the solutions ++2 and --2 are identical, just as -+2 and +-2. therefore, in the case you wrote, the plus/minus sign adds no information, it merely reminds us that square roots do indeed have two real solutions - one positive and one negative.
#178 to #165 - AeroChic
Reply 0
(07/13/2013) [-]
I know that the plus or minus is used to demonstrate that's it's both solutions, but when we first learned about square roots in middle school or whenever, we were taught that they always had two solutions without the plus or minus. However, once into harder math courses, the plus or minus sign was used for clarification. I thought that technically it still had two solutions, but you just used the principal value.
#171 to #165 - pebar
Reply 0
(07/13/2013) [-]
well, actually it's an operator..... same difference
#106 to #81 - danruaul
Reply 0
(07/13/2013) [-]
nice. square root of 4 is also -2. this is nice.
#103 to #81 - articulate
Reply +1
(07/13/2013) [-]
It is only positive 2 in principal.

#84 to #81 - trickytrickster
-5
has deleted their comment [-]
#86 to #84 - Harkonnen
Reply 0
(07/13/2013) [-]
yes it can... (-2)(-2) is what?
#101 to #86 - Wtfisthatshit
Reply 0
(07/13/2013) [-]
+4...you mean (-2)(+2)
#88 to #86 - trickytrickster
-4
has deleted their comment [-]
#91 to #88 - mericaisgreat
Reply +4
(07/13/2013) [-]
Comment Picture
#85 to #84 - sellatio
Reply +1
(07/13/2013) [-]
But every square number has both a positive and negative root, whether or not a sign appears before the root operator.
#87 to #85 - trickytrickster
-2
has deleted their comment [-]
#95 to #87 - sellatio
Reply 0
(07/13/2013) [-]
Length is a scalar, thinking in negative terms confuses calculations, so convention says to work with the positive root. But many times in mathematics, and physics, it is important to consider the negative root also.
#97 to #95 - trickytrickster
-2
has deleted their comment [-]
#92 to #87 - Harkonnen
Reply 0
(07/13/2013) [-]
- sq 4 is 2 or -2.
#96 to #92 - trickytrickster
Reply -1
(07/13/2013) [-]
I'm just gonna go now.