Question
upstudy study bank question image url

Given that: \( \sum_{k=1}^{\infty} 4.3^{2-k} \) 2.1 Is the above geometric series is convergent or divergent. Justify ye 2.2 If further given that \( \sum_{k=p}^{\infty} 4.3^{2-k}=\frac{2}{9} \), determine the value of \( p \).

Ask by Montgomery Cummings. in South Africa
Mar 14,2025

Upstudy AI Solution

Tutor-Verified Answer

Answer

The series is convergent because its common ratio is less than 1. The value of \( p \) is 5.

Solution

Sign in to Unlock Answers for Free!

A Learning Platform Trusted by Millions of Real Students and Teachers.

star-icon Unlock

Answered by UpStudy AI and reviewed by a Professional Tutor

Mind Expander

To determine if the series \( \sum_{k=1}^{\infty} 4.3^{2-k} \) is convergent or divergent, we can first recognize that this is a geometric series. The general form of a geometric series is \( \sum_{k=0}^{\infty} ar^k \), where \( |r| < 1 \) ensures convergence. In this case, we can rewrite the series as: \[ \sum_{k=1}^{\infty} 4.3^{2-k} = 4 \cdot 3^{2} \sum_{k=0}^{\infty} (3^{-1})^k = 12 \cdot \sum_{k=0}^{\infty} (1/3)^k \] Here, the common ratio \( r = \frac{1}{3} \), which is less than 1, so the series converges. Now for the second part, given that \( \sum_{k=p}^{\infty} 4.3^{2-k}=\frac{2}{9} \), we can find the value of \( p \). We first need to express the series starting from \( p \): \[ \sum_{k=p}^{\infty} 4 \cdot 3^{2-k} = 4 \cdot 3^{2} \sum_{k=0}^{\infty} (3^{-1})^{k+p-1} = 4 \cdot 9 \cdot (3^{-p+1}) \cdot \frac{1}{1 - \frac{1}{3}} \] The sum converges to: \[ \sum_{k=p}^{\infty} 4 \cdot 3^{2-k} = 4 \cdot 9 \cdot 3^{-p+1} \cdot \frac{3}{2} = 54 \cdot 3^{-p+1} \] Setting this equal to \( \frac{2}{9} \): \[ 54 \cdot 3^{-p+1} = \frac{2}{9} \] Solving for \( p \): \[ 3^{-p+1} = \frac{2/9}{54} = \frac{1}{243} \] Since \( 243 = 3^5 \), we have: \[ -p+1 = -5 \implies p = 6 \] Thus, the value of \( p \) is 6.

Try Premium now!
Try Premium and ask Thoth AI unlimited math questions now!
Maybe later Go Premium
Study can be a real struggle
Why not UpStudy it?
Select your plan below
Premium

You can enjoy

Start now
  • Step-by-step explanations
  • 24/7 expert live tutors
  • Unlimited number of questions
  • No interruptions
  • Full access to Answer and Solution
  • Full Access to PDF Chat, UpStudy Chat, Browsing Chat
Basic

Totally free but limited

  • Limited Solution
Welcome to UpStudy!
Please sign in to continue the Thoth AI Chat journey
Continue with Email
Or continue with
By clicking “Sign in”, you agree to our Terms of Use & Privacy Policy