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/sci/ - Science & Math

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6173187 No.6173187 [Reply] [Original]

Why is sqrt(9) 3 but not -3? Input sqrt(9)=-3 gives false in wolfram alpha.

>> No.6173197

>>6173187
The symbol sqrt(x) refers to the positive square root of a number. The square roots of a positive number x are sqrt(x) and -sqrt(x).

>> No.6173200

>>6173197
So that's just an agreement? In reality sqrt(9)=3 v -3

>> No.6173209

>>6173200
No, sqrt() doesn't mean square root, it means positive square root.

The square roots of 9 are 3 and -3, but
sqrt(9) = 3, sqrt(9)!=-3.

>> No.6173211

>>6173209
I see. Thanks. Can you reply to my other thread: >>6173210