Abox with a square base is to be made with the restriction that the total dimensions (length + width + height) cannot exceed 90cm. find the dimensions that will have the maximum volume

Okay, so you'll need to find three measurements that, when multiplied together, make 90, two of which are the same. I have as follows:
Height = 10cm
Length = 3cm
Depth = 3cm

3x3x10 = 90 cubic centimetres

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I hope this helps!

Just divide the x axis (the top) by 2 or multiply the y axis (the bottom) by 2

-2x + 7 = 7

subtract 7 from both sides.

-2x = 0

divide both sides by -2.

x = 0

the value of x is equal to 0.