SOLUTION: The area of a rectangle is 1260. Find the dimensions of the rectangle if we know that the length is 48 longer than 3 times the width. Use the quadratic formula in order to solve.

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Question 970280: The area of a rectangle is 1260. Find the dimensions of the rectangle if we know that the length is 48 longer than 3 times the width. Use the quadratic formula in order to solve.
Found 2 solutions by josgarithmetic, Alan3354:
Answer by josgarithmetic(39617)   (Show Source): You can put this solution on YOUR website!
Here is just a start.








Discriminant is and this means you expect to find integers solutions.

and you accept only the positive solution for w.
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
The area of a rectangle is 1260. Find the dimensions of the rectangle if we know that the length is 48 longer than 3 times the width. Use the quadratic formula in order to solve.
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Area = L*W = 1260
(3W+48)*W = 1260
(W + 16)*W = 420
W^2 + 16W - 420 = 0
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation (in our case ) has the following solutons:



For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=1936 is greater than zero. That means that there are two solutions: .




Quadratic expression can be factored:

Again, the answer is: 14, -30. Here's your graph:

===============
W = 14
L = 90
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