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What is the value of the fourth term in a geometric sequence for which [tex]a_1 = 10[/tex] and [tex]r = 0.5[/tex]?

Answer here: ______________________


Sagot :

To find the fourth term in a geometric sequence, we'll use the formula for the nth term of a geometric sequence, which is given by:

[tex]\[ a_n = a_1 \cdot r^{(n-1)} \][/tex]

Here:
- [tex]\( a_1 \)[/tex] is the first term of the sequence.
- [tex]\( r \)[/tex] is the common ratio.
- [tex]\( n \)[/tex] is the term number you want to find.

Given:
- [tex]\( a_1 = 10 \)[/tex]
- [tex]\( r = 0.5 \)[/tex]
- [tex]\( n = 4 \)[/tex]

We need to find the fourth term ([tex]\( a_4 \)[/tex]).

Let's substitute the given values into the formula:

[tex]\[ a_4 = 10 \cdot (0.5)^{(4-1)} \][/tex]

Simplify the exponent:

[tex]\[ a_4 = 10 \cdot (0.5)^3 \][/tex]

Calculate [tex]\( (0.5)^3 \)[/tex]:

[tex]\[ (0.5)^3 = 0.5 \times 0.5 \times 0.5 = 0.125 \][/tex]

Now multiply by the first term ([tex]\( a_1 \)[/tex]):

[tex]\[ a_4 = 10 \cdot 0.125 \][/tex]

[tex]\[ a_4 = 1.25 \][/tex]

Therefore, the value of the fourth term in the geometric sequence is:

[tex]\[ 1.25 \][/tex]