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differentiation

Show that the maximum value of lnx/x3 is 1/3 e-1

I tried the quotient rule which gave me (x2 - lnx(3x2))/x6

​I don't know how to proceed from here can someone help
Original post by bl64
Show that the maximum value of lnx/x3 is 1/3 e-1

I tried the quotient rule which gave me (x2 - lnx(3x2))/x6

​I don't know how to proceed from here can someone help


What do you usually do to find a maximum it minimum?
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bl64
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Original post by TenOfThem
What do you usually do to find a maximum it minimum?


make it = 0 and then differentiate again to work out what type of stationary point it is
but i don't know what number makes it =0
(edited 9 years ago)
Original post by bl64
make it = 0 and then differentiate again to work out what type of stationary point it is
but i don't know what number makes it =0


Yes, make it 0

For a fraction to equal 0 the numerator must equal 0

I assume that the question stated that x was not zero
are mensuration formulae needed to differentiate given in the formulae booklet?:confused:
Original post by Samira siddiqua
are mensuration formulae needed to differentiate given in the formulae booklet?:confused:


The quotient rule is given
Some rules for differentiating trig functions are given

What were you looking for in particular

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