-2^2 = -4? Differentiability at a point: algabraically

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Fraser Stephens

8. oktober 2021 00:14

I got a question wrong in an exercise and when i opened the hint to check where i had gone wrong i noticed the first part of the equation was strange Where x=2 -×^2+3× =-2^2+3(2) The expression was answered as 2 and im guessing -2^2 was evaluated to -4.... is there something im missing? Im sure -2^2=4 and the answer should be 10 or am i wrong. The actual expression continues and this is just the first part of the equation to find f(×) and so it completely messed it up for me...unless im wrong? Am i wrong😲

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Evan Lewis

10. oktober 2021 03:36
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Hi Fraser,

A negative in front of an exponent base means that the exponent rule is applied first, and then the sign is changed. So, the expression -2^2 is really -(2)^2 or -(2^2) which is evaluated to -4.

To get +4 as the result, you would need to write the expression as (-2)^2 to indicate that the negative is also being squared, because by default the negative is not squared.

I hope this helps! Please let me know if you have any additional questions!
Fraser Stephens

10. oktober 2021 23:30
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Thanks Evan,
Shortly after posting this i came to that conclusion.
Kind regards

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-2^2 = -4? Differentiability at a point: algabraically

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