SOLUTION: Solve the following problem: The sum of the squares of two consecutive positve even integers is 340. Find the integers.

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Question 170625This question is from textbook Algebra structure and method book one
: Solve the following problem: The sum of the squares of two consecutive positve even integers is 340. Find the integers. This question is from textbook Algebra structure and method book one

Found 2 solutions by Alan3354, Mathtut:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Solve the following problem: The sum of the squares of two consecutive positve even integers is 340. Find the integers.
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x^2 + (x+2)^2 = 340
x^2 + x^2 + 4x +4 = 340
2x^2 + 4x + 4 = 340
x^2 + 2x -168 = 0
(x-12)*(x+14) = 0
x = 12
x = -14
It's 12 and 14, since it said positive.
12*12 + 14*14 = 340, so it's correct.

Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
two consecutive positive even integers we will call a and a+2
:
a%5E2%2B%28a%2B2%29%5E2=340 distribute
:
a%5E2%2Ba%5E2%2B4a%2B4=340 combine a write as a quadratic
:
2a%5E2%2B4a-336=0 divide by 2
:
a%5E2%2B2a-168=0
system%28a=12%2Ca=-14%29
throw out the negative value since we are looking for positive
so the integers are system%2812%2C14%29
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation aa%5E2%2Bba%2Bc=0 (in our case 1a%5E2%2B2a%2B-168+=+0) has the following solutons:

a%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=%282%29%5E2-4%2A1%2A-168=676.

Discriminant d=676 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-2%2B-sqrt%28+676+%29%29%2F2%5Ca.

a%5B1%5D+=+%28-%282%29%2Bsqrt%28+676+%29%29%2F2%5C1+=+12
a%5B2%5D+=+%28-%282%29-sqrt%28+676+%29%29%2F2%5C1+=+-14

Quadratic expression 1a%5E2%2B2a%2B-168 can be factored:
1a%5E2%2B2a%2B-168+=+1%28a-12%29%2A%28a--14%29
Again, the answer is: 12, -14. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B2%2Ax%2B-168+%29