Question

Solve! The formula for the nth term b of a geometric series is b=ar to the power of n-1. Find n when b=1024, a= 16, and r=2.

Choices are a. 5, b. 6, and c. 7

Answer 1

C. 7

Explanation:

I used this answer and got it right

Answer 2

`b=ar^(n-1)\\\\b=1024=2^(10);\ a=16=2^4;\ r=2;\ n=?\\\\subtitute\\\\2^4\cdot2^(n-1)=2^(10)\ \ \ |use\ a^n\cdot a^m=a^(n+m)\\\\2^(4+n-1)=2^(10)\\\\2^(n+3)=2^(10)\iff n+3=10\ \ \ \ |subtract\ 3\ from\ both\ sides\\\\\boxed{n=7}\to\boxed{c.}`