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Are there two consecutive even numbers whose product is 224?

I want to find if there are two consecutive even integers whose product is 224, and if this can be generalized.

I saw this night before last and almost answered it, but got distracted and lost the question; that'll teach me to bookmark them!

Went out to resolved answers looking for it and found a great number of questions like it or, at least, containing 224; I have to assume that it is an unresolved question floating out there somewhere.

OK, let's set it up. M(M+2) = 224 , or

M^2 + 2M = 224.

Now bear with me; I'm going to digress, but you'll see where I'm going in a minute.

I noticed that 224 is one less than 15^2. This kind of thing stuck in my head when I was doing a lot of sum-and-difference of squares problems.

So if m = 14 (that's one less than 15) then 14^2 + 2x14 = 224....196 + 28 = 224.

So m = 14, and m+2 = 16; 14 x 16 = 224.

Although it's unrelated to the given problem, it seems obvious that there must be just such paired numbers around all the perfect squares.

For example m^2 + 2m = 624 (25^2-1),

which means that m = 24 and m+2 = 26;

24^2 +2x24 = 624

But just to be on the safe side, let's try it with the square of an even number, i.e. 900.

m^2 + 2m = (900-1) ; 29^2 + 2x29 =

841 + 58 = 899, so it would appear to work regardless.

Unfortunately, I don't quite know enough math to prove whether there are are numbers which do not fit this pattern; there may be.

3 Answers

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  • 1 decade ago
    Favorite Answer

    Instead of calling the two even numbers m and m+2, try instead setting n to being the odd number between them, so the two even factors are n-1 and n+1.

    That change in notation will lead to a clear perspective on the pattern you describe.

  • Anonymous
    5 years ago

    Let x be the smallest number. Since they are consecutive even, there will be a difference of two between them, so the other number is x + 2. Make an equation to solve: x(x + 2) = 50,624 x^2 + 2x = 50,624 x^2 + 2x - 50,624 = 0 (x + 226)(x - 224) = 0 x + 226 = 0 or x - 224 = 0 x = -226 or x = 224 ANSWER: -226 and -224 or 224 and 226

  • 1 decade ago

    (m-1)(m+1) = m^2 - 1

    Therefore, for integral m, the number m^2-1 is invariably product of integers (m-1) and (m+1). If m is odd, these numbers will be consecutive even numbers and if m is even, these numbers will be consecutive odd numbers.

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