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I have posted a link there to this topic so the OP can see my work.Mathematics -derivatives?

Hi

Can someone help me to solve the following problem please

A box in the shape of a cuboid has dimensions:

Height: 50 cm

Width: 30 cm

Height: 20 cm

a) Calculate the total transmission restriction area and volume. ( i have done this)

need help with number b

b) Construct a new box with the same restriction area as the first box, but with different dimensions. Which dimensions of the box (length, width and height) give the largest possible volume?

(Hint: second box smallest side will be square. Calling the short side length of x and the long side length of y)

Here's how far I've come:

a)

V = 20 * 30 * 50 = 30000 cm ^ 3

A = 2 (20 * 30) +2 (20 * 50) +2 (30 * 50) = 6200cm ^ 2

b)

V = x ^ 2 * y

A = 2 (x * x) +2 (x * y) +2 (x * y) = 2x ^ 2 +4 xy = 6200 cm ^ 2

I should use the derivatives but I do not know how.