Consider the pair of equations: and . If , then equals
Consider the pair of equations: and . If , then equals
Solution
We have two equations:
... (1)
... (2)
We need to find when .
We add equation (1) and equation (2):
Combining like terms:
Key insight: Notice that we can rearrange this as:
The first three terms form a perfect square pattern.
Since , our equation becomes:
Let . Then our equation becomes:
We need to factor .
This can be written as:
We need two consecutive integers whose product is 56.
Let's find factors of 56:
(difference = 55, not consecutive)
(difference = 26, not consecutive)
(difference = 10, not consecutive)
(difference = 1, these are consecutive!)
Since and are consecutive integers with product 56, we have:
and
Since , we have our answer.
We can check that
Also, since , we have , so (positive) is correct.
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