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A student opened her math book and computed the sum of the numbers on two facing pages. Then she turned to the next page and computed the sum of the numbers on these two facing pages. Finally, she computed the product of the two sums, and her calculator displayed the number 96,717. What were the four page numbers?

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Answer:

The page numbers are 161, 162, 48197, and 48198.

Explanation:

Let the page numbers of the first facing pages be x and x+1, and let the page numbers of the second facing pages be y and y+1.

Then, we have two equations based on the information given in the problem:

x + (x+1) + y + (y+1) = 2x + 2y + 2 = 2(x+y+1)

(x + (x+1))(y+(y+1)) = (2x+1)(2y+1) = 4xy + 2x + 2y + 1

Multiplying these two equations, we get:

2(x+y+1)(4xy+2x+2y+1) = 96,717

Simplifying this expression, we get:

(2x^2+2y^2+5xy+3x+3y+1)(x+y+1) = 48,359

We can see that $48,359$ is a prime number, so it must have two factors: 1 and 48,359 or -1 and -48,359. Since x and y are positive integers, we can discard the negative solutions.

So we have two possibilities:

Case 1: x+y+1 = 1 and 2x^2+2y^2+5xy+3x+3y+1 = 96,717

In this case, x+y=0, which is not possible since x and y are positive integers.

Case 2: x+y+1 = 48,359$ and $2x^2+2y^2+5xy+3x+3y+1 = 2

In this case, x+y=48,358. We can solve the second equation for y in terms of x:

y = \frac{-5x-3\pm\sqrt{25x^2+30x-23}}{4}

Since $y$ must also be a positive integer, we can see that the only solution is y = \frac{-5x-3+\sqrt{25x^2+30x-23}}{4}. We can substitute this into the equation x+y=48,358 to get:

x+\frac{-5x-3+\sqrt{25x^2+30x-23}}{4} = 48,358

Simplifying this equation, we get:

29x^2+7x-185,287=0

Using the quadratic formula, we get:

x = \frac{-7\pm\sqrt{185,321}}{58}

We discard the negative solution, so:

x = \frac{-7+\sqrt{185,321}}{58} \approx 160.71

Since x must be a positive integer, the closest integer solution is x=161.

Substituting this into the equation x+y=48,358, we get:

y = 48,358 - 161 = 48,197

Therefore, the page numbers are 161, 162, 48197, and 48198.

User Sumit Sahoo
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