The houses of a row are numbered consecutively from 1 to 49. Show that there is a value of such that the sum of the numbers of the houses preceding the house numbered is equal to the sum of the numbers of the houses following it. Find this value of .
The houses are numbered consecutively from 1 to 49, which forms a sequence of natural numbers. From the context, using the method of Gauss, the sum of the first n positive integers is given by the formula:
Let the house number be . The sum of the numbers of the houses preceding the house numbered is the sum of the first natural numbers, denoted as . The sum of the numbers of the houses following it is the total sum minus the sum up to , denoted as .
According to the problem, the sum of preceding numbers is equal to the sum of following numbers. Using the hint provided, we can write the equation as:
Substituting the formula for the sum of natural numbers into the equation:
To solve, multiply the entire equation by 2 to eliminate the denominators:
Simplifying this, we get:
Taking the square root of both sides, we find the value of x:
Thus, the house number is 35.
Explanation
The solution utilizes the sum formula for the first natural numbers derived from the Gauss example in the text (). It sets up the equation based on the specific hint provided in the context () to equate the sum of preceding terms with the sum of following terms. Solving the resulting quadratic equation yields the correct house number.
Solution Steps
Step 1: Identify the sequence of house numbers as natural numbers from 1 to 49 and apply the sum formula derived from the Gauss method.
Step 2: Set up the equation based on the problem condition and the provided hint: .
Step 3: Substitute the sum formula into the equation: .
Step 4: Simplify the equation to , which reduces to .
Step 5: Solve for to get , resulting in .