SOLUTION: A rectangular box has dimensions 4ft by 5ft by 5ft. Increasing each dimension of the box by the same amount yields a new box with volume seven times the old. Find how much each dim

Question 274690: A rectangular box has dimensions 4ft by 5ft by 5ft. Increasing each dimension of the box by the same amount yields a new box with volume seven times the old. Find how much each dimension of the orginal box was increased to create the new box. Round your answer to two decimal places.
This is where I started:
0= x^3+20x^2 ---->this part isn't finished, I don't understand how to get it...please help.

Thank You!
Answer by JBarnum(2146) (Show Source): You can put this solution on YOUR website!

x=-14,x=120/13 since x cant be a negative number, then x = 9.230769repeating

each was increased by
check
if it was increased by 4.22 it would=698
hmmm for some reason i failed to calculate things correctly but by doing guess and check i came to the conclusion of 4.23

RELATED QUESTIONS
A rectangular box has dimensions 4ft by 5ft by 5ft. Increasing each dimension of the box... (answered by Alan3354)

A storage company needs to design a new storage box that has twice the volume of its... (answered by josgarithmetic)

9 plates in a 5ft by 5ft box. Each plate has a diameter of 12.if a coin is tossed within... (answered by ewatrrr)

what is the surface area of a triangle that is 4ft by 10ft by 5ft by 4ft by 6ft (answered by Alan3354)

The dimension of a rectangular metal box are 3 cm, 5 cm, and 8 cm. If the first two... (answered by josgarithmetic)

The dimensions of a rectangular metal box are 3 cm, 5 cm, and 8 cm. if the first two... (answered by josgarithmetic)

A rectangular picture frame measures 20cm by 30cm. A new frame is to made by increasing... (answered by unlockmath)

A rectangular garden has dimensions 6m x 4m. If each dimension is increased by the same... (answered by josgarithmetic,ikleyn)