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What is the 8th term in the geometric sequence described by this explicit formula?

[tex]\[ a_n = 3 \cdot 2^{(n-1)} \][/tex]

A. 768
B. 384
C. 49,152
D. 96


Sagot :

To find the 8th term of the geometric sequence, we need to use the given formula of the sequence:

[tex]\[ a_n = 3 \cdot 2^{(n-1)} \][/tex]

Here, [tex]\( a_1 = 3 \)[/tex], which is the first term, and [tex]\( r = 2 \)[/tex], which is the common ratio. We want to find the 8th term ([tex]\( a_8 \)[/tex]), so we substitute [tex]\( n = 8 \)[/tex] into the formula:

[tex]\[ a_8 = 3 \cdot 2^{(8-1)} \][/tex]

Simplifying the exponent:

[tex]\[ a_8 = 3 \cdot 2^7 \][/tex]

Next, we calculate [tex]\( 2^7 \)[/tex]:

[tex]\[ 2^7 = 128 \][/tex]

Now, we multiply this result by 3:

[tex]\[ a_8 = 3 \cdot 128 = 384 \][/tex]

So, the 8th term of the geometric sequence is:

[tex]\[ \boxed{384} \][/tex]

Hence, the correct answer is B. 384.