Math Problem Statement

The first term of an arithmetic sequence is 7, its last term is 70, and its sum is 385. Find the number of terms in the sequence and the common difference.

Solution

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Assignment Questions Overview

(1) Arithmetic and Geometric Series:

  • (a) Find the number of terms in an arithmetic sequence given its first term and the sum.
  • (b) Determine the values of xx for which a geometric series converges and find a specific value of xx for which the sum to infinity is given.
  • (c) Find the first term and the common difference of an arithmetic sequence based on a relationship involving another sequence.

(2) Sequence Summation:

  • (i) Find a general term unu_n in terms of nn.
  • (ii) Find un+1u_{n+1} in terms of unu_n.

(3) Sequence Definition and Analysis:

  • (i) Evaluate specific terms of a sequence.
  • (ii) Find the ratio of consecutive terms for a geometric check.
  • (iii) Find the sum of the sequence's terms.

(4) Series and Summation:

  • (i) Find a constant CC using a given expression.
  • (ii) Compute the sum of a particular sequence expression.

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Math Problem Analysis

Mathematical Concepts

Arithmetic Sequences
Summation
Geometric Sequences

Formulas

Sum of an arithmetic sequence: S = (n/2) * (a + l)
nth term of an arithmetic sequence: a_n = a + (n - 1) * d
Sum to infinity for geometric series: S = a / (1 - r)

Theorems

Summation formula for arithmetic sequences

Suitable Grade Level

Grades 10-12