MAT - Paper 2011 - Q5
Flashcards
What is the general $n$th term for a geometric sequence?
\[U_n = ar^{n-1}\]
How can you rewrite the formula for the sum of the sequence $U _ n = 2^n$?
\[U_n = 2 \cdot 2^{n-1}\]
What is the formula for the sum of the sequence $U _ n = 2^n$?
\[2\left(2^n - 1\right)\]
What is the formula for the sum of the sequence $U _ n = 4^n$?
\[\frac{4\left(4^n - 1\right)}{3}\]
What is the formula for the sum of the sequence $U _ n = 69^n$?
\[\frac{69\left(69^n - 1\right)}{68}\]
\[2 + 2^3 + 2^5\]
How could you formulate this as a more “standard” geometric sequence?
\[U_n = 2\cdot4^{n}\]