Chapter 9: Problem 56
Sum of certain consecutive odd positive integers is \(57^{2}-13^{2}\). Find them.
Short Answer
Expert verified
The consecutive odd positive integers with a sum equal to \(57^2 - 13^2\) are: \[3729, 3731, 3733, ..., 3845\].
Step by step solution
01
Find the actual value of the difference
First, we have to find the actual value of the difference given, which is \(57^2 - 13^2\).
The formula for the difference of two squares is: \[A^2 - B^2 = (A+B)(A-B)\]
Using this formula with \(A = 57\) and \(B = 13\):
\[57^2 - 13^2 = (57+13)(57-13)\]
02
Calculate the values in the brackets
Now, we will find the values of \(57 + 13\) and \(57 - 13\):
\(57 + 13 = 70\)
\(57 - 13 = 44\)
03
Multiply the values to get the total sum
Now, multiply the values obtained in the previous step:
\(70 * 44 = 3080\)
Now we know the sum of the consecutive odd positive integers is \(3080\).
04
Find the series of consecutive odd positive integers
The sum of the first n odd positive integers is given by the formula:
\[S = n^2\]
So, we have to find an odd number which when subtracted from this sum, leaves us with a perfect square.
Now, let's try to find such an odd number that when subtracted from \(3080\), it leaves a perfect square:
For example,
\(3081 - 53 = 3027\) which is not a perfect square.
\(3081 - 15 = 3066\) which is not a perfect square.
\(3081 - 1 = 3080\) which is not a perfect square.
\(3081 - 21 = 3060 \) which is also not a perfect square.
However,
\(3080 - 45 = 3035\)
The result, \(3035\), is not a perfect square, but trying to represent it as the difference of consecutive squares,
\(55^2 - 10^2 = 3025\)
Then:
\(3080 - 45 = 3025 + 5\)
So, the sum of consecutive odd positive integers is equal to \(3080\). Thus, the consecutive odd positive integers are:
\(3025\), \(3027\), \(3029\), ..., \(3045\)
Let's break this sum down into the series:
\[5^2 + 7^2 + 11^2 + ... + 45\]
\[5^2 + (5^2 + 2^2) + (5^2 + 6^2) + ... + 45\]
Now, since there are 5 parts in this sum, we can represent these parts as following:
\[5(5^2) + (0^2 + 2^2 + 6^2 + 8^2 + 12^2)\]
\[5(25) + (0 + 4 + 36 + 64 + 144)\]
\[125 + 248 = 373\]
Now we have a sum of 373 with the consecutive odd positive integers starting at 3729 and ending at 3845. Thus, the consecutive odd positive integers with a sum equal to \(57^2 - 13^2\) are:
\[3729, 3731, 3733, ..., 3845\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Difference of Squares
The difference of squares is a fascinating algebraic identity that states: \(A^2 - B^2 = (A+B)(A-B)\). This formula allows us to express the difference of two squared numbers as a product of a sum and a difference, which simplifies calculations.
- It turns a seemingly complex subtraction into a straightforward multiplication.
- For instance, finding \(57^2 - 13^2\) becomes easier when we calculate \((57+13)(57-13)\).
Sum of Integers
Finding the sum of integers, especially consecutive odd integers, involves specific techniques. An important formula here is \(S = n^2\), where \(S\) is the sum of the first \(n\) odd integers. This formula becomes instrumental when dealing with problems involving consecutive odd numbers.
- Odd integers follow a specific pattern: 1, 3, 5, 7, and so on.
- Each odd integer increases by 2 from the previous one.
Algebra
Algebra is like a puzzle where numbers and letters mix to solve problems. It involves using equations to express relationships between different variables.
- It allows for unknown numbers (like \(x\) or \(n\)) to be solved through equations.
- Algebraic techniques help manipulate expressions and reveal new insights into problems.
Perfect Squares
Perfect squares are numbers that give whole numbers when square-rooted. They are products of an integer multiplied by itself, such as \(1 \times 1 = 1\), \(2 \times 2 = 4\), etc.
- They form the foundation for many mathematical concepts, including the difference of squares.
- Every positive integer has a unique perfect square closest to it.