Is it because elnx = xlne?
Would they expect a maths adv student to do that?
Multiplying is much less complicated lol!
One last question, how would I test it? lol, whats on either side of e?
So once I've raised them both, how do I get to x=e?
& I tried that but its all increasing (answer says max)
Hm, it sounds like you haven't been given a good explanation yet. One of the most important concepts is to raise log by e or to raise e by log; they are sort of like inverses of each other, and can cancel each other out. But, not like multiplication/division, they are powers of each other. (You're going to need a better explanation of the whole log and e relation, because it's too easy to just take these things for granted)
Anyway, it should be a maximum; let x = 2, y' = (1 - ln(2))/4 > 0, and when x = 3, y' = (1 - ln(3))/9 < 0.
Mechanical Engineering UNSW '15
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