SOLUTION: I am not sure how to categorize my question. My nephew and I would like to find the right formula to calculate the following: A rectangle Side A is x + 20 Side B is x Ar

Question 150725: I am not sure how to categorize my question. My nephew and I would like to find the right formula to calculate the following:
A rectangle
Side A is x + 20
Side B is x
Area = 576
We know that x = 16 but we do not know a formula that gives us this answer (16).
Any help would be greatly appreciated
Paul
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
.
The problem assumes that you know the formula for any rectangle is:
area = width * length
.
Therefore, if you have:
Side A is x + 20
Side B is x
Area = 576
.
Then, your formula would be:
576 = x(x+20)
576 = x^2 + 20x
0 = x^2 + 20x - 576
.
Factoring the right side we have:
0 = (x-16)(x+36)
the solutions are then
x = {-36, 16}
.
It doesn't make sense to have a "negative" length for a side therefore the solution MUST be:
x = 16 (Side B)
and
x+20 = 36 (Side A)

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