posted by Anonymous on .
An open box contains 80cm^3 and is made from a square piece of tinplate with 3cm squares cut from each of its four corners. Find the dimensions of the original piece of tinplate.
since length and width are the same, and when the box is folded the height will be 3cm,
Since the width has 2 3cm sections cut out of it, I said:
To find x, I tried subbing w=x+6 into my previous equation:
Which expands as:
What do I do next? I tried the quadratic formula to get x, but ended up with two negative numbers, which is not a valid solution. Please help me... Was my process wrong?