Question

Find maximum and minimum
y= 3x e^(-x) + x

Answer 1

Derivative!!!

Answer 2

of cuz i know is derivative..==

Answer 3

cuz sometimes u leave the number out of derivative
but this one u include it..that's what i dont get

Answer 4

Not sure what you mean leaving the number out. This is just a straight out derivative and finding the critical points. So when f'(x)=0
This means when the derivative equals zero find x.

Answer 5

Not sure if this is right. @hero please help me. Is this right?

Answer 6

All you have to do is graph it first to get approximate values. Then find f'(x) and f"(x)

Answer 7

so i must graph it?

Answer 8

I'm pretty sure the minimum is -infinity and maximum is + infinity. You're not going to be able to figure that out algebraically. You just have to graph it and see for yourself.

Answer 9

oh ok thanks
my textbook gives an algebraic value
but that's when u include 3 in the derivative

Answer 10

my textbook does product rule of (3x)(e^-x) + x

Answer 11

but sometimes in other equations , u can leave out the number, like 1000 (e^t+1) , i think u dont need to derivative the 1000 in here

Answer 12

Yeah, but you won't get anywhere as far as finding an actual min and max value.

Answer 13

so do i juz pick random points and put it on the graph?

Answer 14

Why would you do that?

Answer 15

What would be the point of doing that?

Answer 16

then..? find critical points?

Answer 17

You said in your original question you had to find the min and max values.

Answer 18

yes dont u find critical points and test for max and min?

Answer 19

what my teacher taught is to find critical points, compare it with the restriction , and then determine max and min

Answer 20

I guess you mis-understood my previous posts.

Answer 21

ohh...okkk..but gotta sleep now.. 1am already.. thks for ur help