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I don't know how to solve it.

I don't know how to solve it.-example-1
User Bgerth
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1 Answer

7 votes

Explanation:

Take the first derivative


(d)/(dx) ( {x}^(3) - 3x)


3 {x}^(2) - 3

Set the derivative equal to 0.


3 {x}^(2) - 3 = 0


3 {x}^(2) = 3


{x}^(2) = 1


x = 1

or


x = - 1

For any number less than -1, the derivative function will have a Positve number thus a Positve slope for f(x).

For any number, between -1 and 1, the derivative slope will have a negative , thus a negative slope.

Since we are going to Positve to negative slope, we have a local max at x=-1

Plug in -1 for x into the original function


( - 1) {}^(3) - 3( - 1) = 2

So the local max is 2 and occurs at x=-1,

For any number greater than 1, we have a Positve number for the derivative function we have a Positve slope.

Since we are going to decreasing to increasing, we have minimum at x=1,

Plug in 1 for x into original function


{1}^(3) - 3(1)


1 - 3 = - 2

So the local min occurs at -2, at x=1

User Cromir
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