Square of One more than the Larger Part

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This isn't really much of an algebra problem but different people are giving me different interpretations of " Square of One more than the Larger Part ". I've been given

" Separate 17 into two parts. So that the sum of their squares is equal to the "SQUARE OF ONE MORE THAN THE LARGER PART". Find the Smaller Part. "

I interpreted it myself; and I got

$x^2 + y^2 = (y^2 + 1)^2 = 17$

I don't think this works. I feel I have misinterpreted the problem. Other people have other interpretations too but they don't work either.

The correct answer is 5.

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"Separate $17$ into two parts."

That tells me you should set up $x+y = 17$ (equation 1)

"The sum of the squares of the parts is equal to the square of one more than the greater part."

We can let $y$ be the greater part without any loss of generality (which makes $x$ the smaller part). That means that $x^2 + y^2 = (y+1)^2$. (equation 2).

Now you have to solve the two equations simultaneously.

Start by manipulating equation 2:

$x^2 = (y+1)^2 - y^2 = 2y+1$

$y = \frac{1}{2}(x^2 - 1)$

Substitute that expression for $y$ into equation 1 to get:

$x + \frac{1}{2}(x^2 - 1) = 17$

After rearrangement, you should get the quadratic:

$x^2 + 2x - 35 = 0$

which can be factorised:

$(x+7)(x-5) = 0$

So $x=-7$ or $5$.

Here we generally discard the negative root as splitting a number into two parts generally refers to natural number parts. Perhaps this needs better clarification in the question. But assuming this is the case, the only admissible solution is $x=5$.