Math Problem Statement
Consider a finite arithmetic sequence of positive integers. Among its terms are the numbers 28, 52 and 82. The sum of all terms in the sequence is 1769. Find the smallest and largest terms in the sequence. d=3
Solution
To solve this problem, let's consider the given finite arithmetic sequence. The sequence has a common difference , and it contains the terms 28, 52, and 82. We are also given that the sum of all terms in the sequence is 1769.
Step 1: General Form of the Arithmetic Sequence
The general term of the arithmetic sequence can be written as: where is the first term, is the common difference, and is the position of the term in the sequence.
Step 2: Express the Known Terms
We are given that 28, 52, and 82 are terms in the sequence. Let , , and for some integers and . Then we can express these terms as:
Step 3: Solve for the Differences Between Indices
Subtract the first equation from the second: [ 52 - 28 = [a_1 + (j-1) \cdot 3] - [a_1 + (i-1) \cdot 3] ]
Now subtract the second equation from the third: [ 82 - 52 = [a_1 + (k-1) \cdot 3] - [a_1 + (j-1) \cdot 3] ]
So, we have and .
Step 4: Write the Terms Using
Now, we can express the positions of these terms in terms of :
Step 5: Sum of the Sequence
The sum of all terms in the sequence is given by: where is the total number of terms. We are given .
Step 6: Calculate the First Term
Since , we can express as: Substituting into the other terms:
Step 7: Determine the Smallest and Largest Terms
To find the smallest and largest terms, note that the sequence starts at and ends at . The largest term is .
Given :
Since we already have the three terms that fit in, the sequence should contain terms (based on and ). The smallest term will be and the largest term . We find:
Thus, the sequence starts at 10 (smallest term) and ends at 82 (largest term).
Final Answer:
The smallest term is and the largest term is .
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Math Problem Analysis
Mathematical Concepts
Arithmetic Sequences
Sum of Arithmetic Series
Formulas
General term of an arithmetic sequence
Sum of an arithmetic series
Theorems
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Suitable Grade Level
Grades 9-12
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