SOLUTION: The volume of a rectangular solid is 990 cubic cm and its total area is 675 sq. cm. If its altitude is 20 cm, find the dimensions of the base.

Question 946067: The volume of a rectangular solid is 990 cubic cm and its total area is 675 sq. cm. If its altitude is 20 cm, find the dimensions of the base.
Answer by josgarithmetic(39630) (Show Source): You can put this solution on YOUR website!
Let x and y be the bottom dimensions.
Volume is .
Total area is .

Simplify the system.

A bit of some algebra steps, but solve the first equation for either variable and substitute into the second equation.--------------BUT recognize that both equations have a term, 2xy. Make use of that!!

, substituting for 2xy.

NOW use the first equation again but solved for either variable in terms of the other variable: .
Substitute for that variable.

----Do you know what was done for this step?

Not sure if that is factorable. Find discriminant.

, the big factor being prime.
Discriminant is .

Not really finished but more than half the way to it.
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