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Mathematics 20 Online
OpenStudy (anonymous):

Can someone help me with this problem please

OpenStudy (anonymous):

OpenStudy (anonymous):

can you help me

OpenStudy (loser66):

what do you think, give me your idea first, it's not a piece of cake

OpenStudy (anonymous):

um I think that we have to put the e^k where ever we see an x first

OpenStudy (loser66):

how about the "global minimum value of fx"?

OpenStudy (anonymous):

yeah that is where I get confused with these problems

OpenStudy (loser66):

is it not the vertex of parabola? since it's is upward, so the minimum value is the vertex of it .

OpenStudy (anonymous):

ok

OpenStudy (anonymous):

so then 2

OpenStudy (anonymous):

ok

OpenStudy (anonymous):

f'(x)=x+2xlnx

OpenStudy (loser66):

=0 when?

OpenStudy (anonymous):

?

OpenStudy (loser66):

is it right with the derivative?

OpenStudy (anonymous):

yes

OpenStudy (loser66):

sorry, you are right,

OpenStudy (anonymous):

so then what?

OpenStudy (loser66):

and that derivative =0 to get the x value of the vertex,

OpenStudy (loser66):

=0 when?

OpenStudy (anonymous):

so then add 0 where there is an x

OpenStudy (loser66):

no, it =0 when x(1+2lnx)=0 iff x =0 or 2lnx =-1 (reject)

OpenStudy (anonymous):

oh ok

OpenStudy (loser66):

sorry, not that, not reject, reject x =0

OpenStudy (loser66):

accept the value of 2lnx = -1 ---> lnx = -1/2 ---> x = e^-1/2

OpenStudy (loser66):

combine with yours x = e^k ----> k = 1/2

OpenStudy (loser66):

got it?

OpenStudy (anonymous):

yes

OpenStudy (loser66):

ohoh -1/2

OpenStudy (anonymous):

why -.5

OpenStudy (loser66):

sorry, so tired , really got?

OpenStudy (loser66):

yeap

OpenStudy (anonymous):

so then -.5 is the final answer

OpenStudy (loser66):

yeap

OpenStudy (loser66):

I think so. if not, I hand off,

OpenStudy (anonymous):

thanks

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