# surface area find function

• Feb 26th 2007, 06:36 PM
supermanismyhero
surface area find function
the question: a box with a volume of 5000. the base is a squre. find the surface are

i tired it and got 2x^2+20000/x but someone told me it was 2x^2+40000/x

• Feb 26th 2007, 07:25 PM
Jhevon
Quote:

Originally Posted by supermanismyhero
the question: a box with a volume of 5000. the base is a squre. find the surface are

i tired it and got 2x^2+20000/x but someone told me it was 2x^2+40000/x

how exactly did you come up with that answer?
• Feb 27th 2007, 12:03 AM
earboth
Quote:

Originally Posted by supermanismyhero
the question: a box with a volume of 5000. the base is a squre. find the surface are

i tired it and got 2x^2+20000/x but someone told me it was 2x^2+40000/x

Hi,

to me your solution looks OK.

I'll do the problem and you can check your homework:

The volume of the cuboid is calculated by:

V = x² * h . Thus h = V / x². With your problem h = 5000/x²

The surface consists of 2 squares and 4 rectangles with length = height of the cuboid and width = side of the square. Therefore you get:

A = 2*x² + 4*x*h = 2*x² + 4*x*5000/x²

You can simplify the last summand by cancelling out one x. So you get:

A = 2*x² + 4*5000/x = 2*x² + 20000/x

And that's exactly what you've got. Congratulations!

EB