Question

find the sum of a 9-term geometric sequence when the first term is 4 and the last term is 1,024 and select the correct answer below. 682 2,044 2,048 678

Answer 1

Hello,

$u_{1} =4\\ u_{2} =4*q\\ u_{3} =4*q^2\\ ...\\ u_{9} =4*q^8\\\\ ==\textgreater\ 4*q^8=1024\\ ==\textgreater\ q^8=256\\ ==\textgreater\ q=2\mbox{( and there is a problem in the question) } \ or \ q=-2\\ if\ q=2 \ then\ \sum_{i=0}^{8}\ 4*(2)^i= 4*\dfrac{1-2^9}{1-2} =2044\\ if \ q=-2 \ then\ \sum_{i=0}^{8}\ 4*(-2)^i= 4*\dfrac{1-(-2)^9}{1+2} =684$

Answer B (but see the problem)

Answer 2

Answer:

I just did the test and the answer was 2,044.

Step-by-step explanation:

I Promise just trust me