Does anyone want to discuss about GRE Subject Test - Maths with me?

[Sumit]

Please Let me know if you find any on NET

[ish]

A Q on maxima and minima...

A rectangle in the fourth Quadrant of the xy plane has adjacent sides on the coordinate axes. if the vertex opposite (0,0) is on y=logx, what is the maxm area this rect can have?

The books says, Area A= x(-logx) as in the interval (0,1) the value of logx is negative.

But shouldnt the lengths be positive? and the area be x.logx ???

Someone help me!!!

[Naseer Asif]

ish,



I have studied your question in detail. Since all the values of y in fourth quadrant are negative, so we will have to take absolute value of y. i.e. | y | = - y = - log x (because y<0). So, definitely the area will be A = x | y | = x(- log x). Maximum area will be 1/e (in case of natural logrithm) or 1/10 (in case of log of base 10).

[Naseer Asif]

ish,
in case of log of base 10, the maximum area will be 1/(e ln 10) ;ln denote the natural logrithm.