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secondary 4 | A Maths
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kathy2
Kathy2

secondary 4 chevron_right A Maths chevron_right Singapore

Thank you

Date Posted: 1 week ago
Views: 13

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Eric Nicholas K
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Eric Nicholas K
Eric Nicholas K
1 week ago
The modulus which the other tutor has put in the answer is not required in the O Levels but required in the A Levels.

The modulus sign is there to take into account the fact that 1/x is valid for all non-zero values of x, and therefore its integral should also be valid for negative x, but we know that the x in ln x cannot be negative, hence the modulus sign.

When we differentiate ln x, the x in ln x is in the first place only defined for x > 0, so its derivative x is also defined (at x > 0). Which is why you do not see any modulus at all during differentiation.
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Marcus Leow Jia Xian
Marcus Leow Jia Xian's answer
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Hope this helps!