Why is the Absolute Value of X Taken in the Derivative of Arc Secant?

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SUMMARY

The derivative of the arc secant function requires the absolute value of x in the denominator to ensure the expression remains valid for its defined domain. The inverse secant function is strictly defined for x values less than -1 or greater than 1. The presence of the square root in the derivative introduces a "plus or minus" factor, which, when combined with x, guarantees that the derivative is always positive. Therefore, the absolute value is not to prevent zero in the denominator, as x=0 is outside the function's domain.

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wazzup
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Hello there

In the derivative of the arc secant, why is the absolute value of x ( which is present in the denominator) taken? Is this to prevent the possible of having a zero ( and making the whole expression undefined ? )


Thanks
 
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wazzup said:
Hello there

In the derivative of the arc secant, why is the absolute value of x ( which is present in the denominator) taken? Is this to prevent the possible of having a zero ( and making the whole expression undefined ? )


Thanks
No, absolute value won't do that: |0|= 0 so you still can have in the denominator. (And the derivative is undefined for x= 0.) Strictly speaking the inverse secant is only defined for x less than -1 or greater than 1. It is because of the square root in the derivative that we have a "plus or minus" which, combined with x itself, makes the derivative always positive.
 

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