Question

Anyone knows why the domain is 0 < x < 10 sqrt (2)
plz see the picture attached

Answer 1

It is an optimization problem

Answer 2

maybe some constraint given for height??

Answer 3

but how u know it is 10 sqrt （2）

the question itself didnt give any restriction

Answer 4

so there are no constraints??

Answer 5

oh it actually says The machinery available cant fabricate material smaller than 2 cm in length

but it doesnt really affect that 10sqrt (2)

Answer 6

The volume of a square-based rectangular cardboard box is to be 1000 cm3. Find the dimensions so that the quantity of material used to manufacture all 6 faces is a minumum. Assume that there will be no waste material. The machinery avaiable cannot fabricate material smaller in lenght than 2 cm.

Answer 7

or what is the domain in this question? for x

Answer 8

mathematically should be greater than zero ... or less than zero (technically discarded)

Answer 9

yea, but since the question says mustbe more than 2
so the domain is only x > 2?

Answer 10

cuz i think the domain is only for surface area but not volume

Answer 11

maybe the question is asking you to find the absolute maximum ...

Answer 12

yes it is
but the teacher tells us to findthe domain too

Answer 13

the domain is value of x .. surface area and volume are range

Answer 14

what do u mean? i thought they are the same...

Answer 15

your given function is A(x)
the value of A(x) is the range, and x is the domain

Answer 16

http://www.wolframalpha.com/input/?i=y+%3D+2x%5E2%2B4000%2Fx

mathematically x can have any value excluding 0, that is your domain

Answer 17

ohhh but i have other questions that the domain has 2 restrictions .. let me see if i can figure it out first

but thanks! i mixed up domain and range!!

Answer 18

here your domain is [0. 10sqrt(2)] ... i think it should be (0. 10sqrt(2)] since function is discontinuous at 0
adding another constraint that machine cannot make x less than 2, the new domain must be
[2. 10sqrt(2)]

Answer 19

but i dont know where that 10sqrt(2) is from.. cuz that one is juz thetextbook answer

Answer 20

And u know for A = 1000x - 2x^2
i checked on that website, it shows domain is xer
but actually the restriction is 0< x< 500

Answer 21

not .. the question has given you the domain

Answer 22

which ques u talking abt?

Answer 23

for this function A = 1000x - 2x^2, the domain is whole set of real number,
but you can specify domain while defining function

Answer 24

OHHHH yes I get
x can be any numbers
but the question itself has restriction

but the first question only tells u minimum is 2
so i guess the domain there will juz be x> 2

Answer 25

yes ...!
some function are defined that way ... with a restriction.

Answer 26

Thanks ! srry for taking so much of ur time :)

Answer 27

it's all right ... you can learn a let by teaching too