Three ratios that are equivalent to 8:5
1 answer:
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Answer:
C. The 6th term is positive/negative 80
Step-by-step explanation:
Given
Geometric Progression
Required
To get the 6th term of the progression, first we need to solve for the first term and the common ratio of the progression;
To solve the common ratio;
Divide the 7th term by the 5th term; This gives
Divide the numerator and the denominator of the fraction by 40
----- equation 1
Recall that the formula of a GP is
Where n is the nth term
So,
Substitute the above expression in equation 1
becomes
Square root both sides
r = ±
Next, is to solve for the first term;
Using
By substituting 160 for T5 and ± for r;
We get
Multiply through by 16
Now, we can easily solve for the 6th term
Recall that the formula of a GP is
Here, n = 6;
r = ±
So,
or
or
or
±80
Hence, the 6th term is positive/negative 80