Math Problem Statement

The table uploaded by the user represents sequences with geometric progression parameters. The user needs to find the values for the missing parameters in the table for each geometric sequence.

Solution

The table you've uploaded represents sequences with geometric progression parameters. For each row, the values for a1a_1 (first term), rr (common ratio), nn (term number), ana_n (nth term), and SnS_n (sum of the first n terms) are provided or need to be found.

Let's break this down row by row, using the geometric sequence formulas:

  • an=a1×rn1a_n = a_1 \times r^{n-1} (formula for the nth term)
  • Sn=a1×1rn1rS_n = a_1 \times \frac{1 - r^n}{1 - r} (sum of the first n terms, for r1r \neq 1)

Row 1:

  • a1=3a_1 = 3, r=12r = \frac{1}{2}, n=6n = 6
  • Find ana_n and SnS_n.

Using an=a1×rn1a_n = a_1 \times r^{n-1}: a6=3×(12)61=3×132=332a_6 = 3 \times \left(\frac{1}{2}\right)^{6-1} = 3 \times \frac{1}{32} = \frac{3}{32}

Now, for SnS_n: S6=3×1(12)6112=3×116412=3×636412=3×12664=37864=5.90625S_6 = 3 \times \frac{1 - \left(\frac{1}{2}\right)^6}{1 - \frac{1}{2}} = 3 \times \frac{1 - \frac{1}{64}}{\frac{1}{2}} = 3 \times \frac{\frac{63}{64}}{\frac{1}{2}} = 3 \times \frac{126}{64} = \frac{378}{64} = 5.90625

Row 2:

  • a1=4a_1 = 4, n=5n = 5, a5=1024a_5 = 1024
  • Find rr and SnS_n.

Using an=a1×rn1a_n = a_1 \times r^{n-1} with a5=1024a_5 = 1024: 1024=4×r51=4×r41024 = 4 \times r^{5-1} = 4 \times r^4 r4=10244=256r=4r^4 = \frac{1024}{4} = 256 \quad \Rightarrow \quad r = 4

Now, calculate S5S_5: S5=4×14514=4×110243=4×10233=4×341=1364S_5 = 4 \times \frac{1 - 4^5}{1 - 4} = 4 \times \frac{1 - 1024}{-3} = 4 \times \frac{-1023}{-3} = 4 \times 341 = 1364

Row 3:

  • a1=3a_1 = 3, r=3r = 3, n=5n = 5, a5=81a_5 = 81
  • Find SnS_n.

Using Sn=a1×rn1r1S_n = a_1 \times \frac{r^n - 1}{r - 1}: S5=3×35131=3×24312=3×2422=3×121=363S_5 = 3 \times \frac{3^5 - 1}{3 - 1} = 3 \times \frac{243 - 1}{2} = 3 \times \frac{242}{2} = 3 \times 121 = 363

Row 4:

  • a1=4a_1 = 4, r=2r = -2, n=5n = 5, a5=128a_5 = -128
  • Find SnS_n.

Using Sn=a1×rn1r1S_n = a_1 \times \frac{r^n - 1}{r - 1}: S5=4×(2)5121=4×3213=4×333=4×11=44S_5 = 4 \times \frac{(-2)^5 - 1}{-2 - 1} = 4 \times \frac{-32 - 1}{-3} = 4 \times \frac{-33}{-3} = 4 \times 11 = 44

Row 5:

  • a1=5a_1 = 5, r=13r = \frac{1}{3}, n=7n = 7, a7=13a_7 = \frac{1}{3}
  • Find SnS_n.

Using Sn=a1×1rn1rS_n = a_1 \times \frac{1 - r^n}{1 - r}: [ S_7 = 5 \times \frac{1 - \

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Math Problem Analysis

Mathematical Concepts

Geometric Progression
Sequences and Series

Formulas

a_n = a_1 * r^(n-1)
S_n = a_1 * (1 - r^n) / (1 - r)

Theorems

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Suitable Grade Level

Grades 10-12