SOLUTION: The perimeter of one square exceeds that of another by 16 and its area is 44 less than the 4 times the area of the other. What is the length of the side of each square?

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Question 165936: The perimeter of one square exceeds that of another by 16 and its area is 44 less than the 4 times the area of the other. What is the length of the side of each square?

Answer by nerdybill(7384) About Me  (Show Source):
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The perimeter of one square exceeds that of another by 16 and its area is 44 less than the 4 times the area of the other. What is the length of the side of each square?
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Perimeter of any square equals 4 times the length of a side.
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Let x = length of a side of smaller square
and y = length of a side of larger square
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From:"The perimeter of one square exceeds that of another by 16"
4x = 4y+16
dividing through by 4:
x = y + 4 (equation 1)
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From:"its area is 44 less than the 4 times the area of the other"
x^2 = 4y^2 - 44 (equation 2)
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Substitute the value of 'x' from equation 1 into equation 2 and solve for y:
x^2 = 4y^2 - 44
(y + 4)^2 = 4y^2 - 44
y^2 + 8y + 16 = 4y^2 - 44
8y + 16 = 3y^2 - 44
16 = 3y^2 - 8y - 44
0 = 3y^2 - 8y - 60
Solving using the quadratic equation will yield:
x = {6, -3.33333333333333}
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We can toss out the negative answer leaving:
x = 6
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To find y, substitute x into equation 1 and solve:
x = y + 4
6 = y + 4
2 = y
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Solution: 6 and 2
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Below is the details of the quadratic solution:
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Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 3x%5E2%2B-8x%2B-60+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%28-8%29%5E2-4%2A3%2A-60=784.

Discriminant d=784 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--8%2B-sqrt%28+784+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-8%29%2Bsqrt%28+784+%29%29%2F2%5C3+=+6
x%5B2%5D+=+%28-%28-8%29-sqrt%28+784+%29%29%2F2%5C3+=+-3.33333333333333

Quadratic expression 3x%5E2%2B-8x%2B-60 can be factored:
3x%5E2%2B-8x%2B-60+=+3%28x-6%29%2A%28x--3.33333333333333%29
Again, the answer is: 6, -3.33333333333333. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+3%2Ax%5E2%2B-8%2Ax%2B-60+%29