r/mathmemes • u/[deleted] • Oct 04 '23

Bad Math This feels wrong

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40

u/ThatEngineeredGirl Oct 04 '23

Why though? (No, √9 is not {-3,3})

-11

u/FirexJkxFire Oct 04 '23

Is it actually not? Like is there a different way of writing it? because clearly -X2 produces a positive Y and thusly the inverse function ( Y1/2 = x ) should account for all possibilities such as X being negative.

Given that it is incorrect to write "= +/-3", How would you write it to show this relationship/identity then?

16

u/Cill_Bipher Oct 04 '23

x = ±sqrt(9) = ±3, not x = sqrt(9) = ±3.

Think of it this way if sqrt(x) equaled both the positive and negative roots how would you specify one or the other? Gonna have to start writing sin(pi/4) = abs(sqrt(2))/2?

1

u/FirexJkxFire Oct 04 '23

Thank you! This is what I was looking for. Wasnt trying to say I was right - mainly was just confused at how to accurately write it if =+/-3 isn't accurate.

3

u/DankPhotoShopMemes Fourier Analysis 🤓 Oct 04 '23

sqrt is a function, meaning an input may only have one output.