#### Stouffville

##### New member

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All I got is

V=(x-50)(x-30)(x)

I do not understand what to do after

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- Thread starter Stouffville
- Start date

- Joined
- Sep 17, 2021

- Messages
- 33

All I got is

V=(x-50)(x-30)(x)

I do not understand what to do after

- Joined
- Nov 12, 2017

- Messages
- 14,457

Please show how you got that equation. It is incorrect.

All I got is

V=(x-50)(x-30)(x)

I do not understand what to do after

A labeled picture will help. What will be each dimension of the box?

Once you have the right expression for volume, you can use it to write an inequality, and try to solve it.

D

What is 'x'?

All I got is

V=(x-50)(x-30)(x)

I do not understand what to do after

- Joined
- Sep 17, 2021

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- 33

D

I ask again - what is 'x'?

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That's the correct equation, assuming that x is the side of each square. (You really need to define variables before stating equations.)

Now set your expression equal to 4000 and solve to find when the volume willAn open-topped box can be made from a sheet of aluminium measuring 50 cm by 30 cm by cutting congruent squares from the four corners and folding up the sides. Write a polynomial function to represent the volume of the box, and then use it to determine thedimensions that result in a volumecm^3greater than4000

Since this is a

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(50-2x)(30-3x)x

= 6x^3 - 210x^2 + 1500x

WIll the rational roots be 2/50 or 3/30 because my teacher never taught me about rational root

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You need to set this equal to 4000, as I said:

(50-2x)(30-3x)x

= 6x^3 - 210x^2 + 1500x

WIll the rational roots be 2/50 or 3/30 because my teacher never taught me about rational root

6x^3 - 210x^2 + 1500x = 4000

Now you have to get this all on one side and factor that side.

If you haven't learned about rational roots, then you'll need to tell us what you

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This is not a school it is a private school for credit of math. But the teacher does not teach at all.You need to set this equal to 4000, as I said:

6x^3 - 210x^2 + 1500x = 4000

Now you have to get this all on one side and factor that side.

If you haven't learned about rational roots, then you'll need to tell us what youhavelearned, or we can't really help you. We have no idea what methods you can use unless you tell us. What topics have been recently covered in class? Are you perhaps allowed to use technology like graphing calculators?

- Joined
- Oct 29, 2019

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Sorry I got it how is it (50-2x)(30-2x)x

will it be :

(50-2x)(30-3x )x

Like @Dr.Peterson wrote, your first expression was correct, but then you copied it out incorrectly in the next post with a "3x" (and therefore the subsequent expansion is wrong too)

Last edited:

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I didn't ask what kind of school you are in, or whether you have a good teacher. I asked two things:This is not a school it is a private school for credit of math. But the teacher does not teach at all.

So whatmy teacher never taught me about rational root

With no context, the the only methods I can think of for you to use are rational roots and technology.

To make sure we agree on the equation, it should bewill it be :

(50-2x)(30-3x)x

= 6x^3 - 210x^2 + 1500x

(50-2x)(30-2x)x = 4000

which expands to

4x^3 - 160x^2 + 1500x - 4000 = 0

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I have done long divide, some factor themor and reminder themor and that is it

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It too late now I already hand it in with out the answer for this question.

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I have done long divide, some factortheoremand remaindertheoremand that is it

Those theorems are commonly taught leading up to the rational root theorem, and are part of the work of applying it. Without the RRT, you could at least try dividing by a few small numbers to see if you can find a zero; from that, you could find the others using the factor theorem.It too late now I already hand it in with out the answer for this question.

And I hope you at least showed your work as far as you could get.