# Thread: Stuck on factorisation after differenting

1. ## Stuck on factorisation after differenting

I have a very long question but I am stuck on factorizing the value of the differentiation I have found to find the x value.

Here is the differentiation: 2πx^3 - 2πx - 4x +80.

Do you think it would be a good idea to multiply the π with 2 to remove it. The result will be a decimal value but that will be had to work with as well. This will affect the x values right.

Thanks.

2. ## Re: Stuck on factorisation after differenting

Originally Posted by Googl
I have a very long question but I am stuck on factorizing the value of the differentiation I have found to find the x value.

Here is the differentiation: 2πx^3 - 2πx - 2x +80.

Do you think it would be a good idea to multiply the π with 2 to remove it. The result will be a decimal value but that will be had to work with as well. This will affect the x values right.

Thanks.
about all you can do is factor out 2 from the posted expression.

what are you trying to find? note that posting the original problem may give others some insight toward a solution.

3. ## Re: Stuck on factorisation after differenting

Originally Posted by skeeter
about all you can do is factor out 2 from the posted expression.

what are you trying to find? note that posting the original problem may give others some insight toward a solution.
...which will become: πx^3 - πx - 2x + 40

The question is very long, I don't think I would be able to type it here. But I am given the perimeter of a shape and I am supposed to find the area in terms of x, then find the value of x using calculus. You get the idea. I have used the given perimeter value to exclude the y value (by writing it in terms of x). Now I have the area in terms of x which I have differentiated to to give the result above.

Do you think it would be okay to use trail and improvement?

4. ## Re: Stuck on factorisation after differenting

how did you end up with a cubic expression for area?

let me take a wild guess ... does your original problem involve maximizing the area of a "Norman Window" given its perimeter?

5. ## Re: Stuck on factorisation after differenting

Originally Posted by skeeter
how did you end up with a cubic expression for area?

let me take a wild guess ... does your original problem involve maximizing the area of a "Norman Window" given its perimeter?
No it does not, it is the combination of different shapes from a problem the finding the perimeter and areas of the shapes. The rest you know.

Yes the problem was the cubic expression, but I have solved that now and managed to complete the rest of the question.

Thanks for the help.