posted by Cadmus on .
An open-topped box can be created by cutting congruent squares from each of the four corners of a piece of cardboard that has dimensions of 20cm by 30cm and folding up the sides. Determine the dimensions of the squares that must be cut to create a box with a volume of 1008cm^3.
I don't get this because x and cm aren't interchangeable digits.
no idea what your complaint is about. x is a variable, and its units are cm. Multiply the three expressions and you get cm^3.
x(20-2x)(30-2x) = 1008
4x^3 - 100x^2 + 600x - 1008 = 0
scale down by 4:
x^3 - 25x^2 + 150x - 252 = 0
252 = 2*2*3*3*7
The only integer root is x=3, so the required box is
3×14×24 = 1008
Actual length = 23•8m 1cm to 2m