Question

f(x) = x ln x restricted to positive x.
find if function is increasing or decreasing

Answer 1

First, find the derivative of f(x) with help from our friend, Product Rule.

Answer 2

f'(x) is lnx+1

Answer 3

i did

Answer 4

Is it positive or negative?

Answer 5

0 to .368 its -
and .368 to infinity is +
thats what i got , is it right or wrong?

Answer 6

Yes that's true

Answer 7

coool thanks so thats the answer?

Answer 8

I'd write 1/e instead of .368

Answer 9

Right, since the derivative is positive or negative on those intervals, f(x) is either incrasing or decrasing, respectively, on those intervals.

Answer 10

oh i have to form intervals like (0,0.368)
or i just write 1/e

Answer 11

Err, depends on you. 1/e looks nicer I suppose lol.

Answer 12

haha ok thanks