In a geometric sequence, the first term, a1, is equal to 3 , and the third term, a3, is equal to 192 . Which number represents the common ratio of the geometric sequence?r=6r=7r=8r=9
Q. In a geometric sequence, the first term, a1, is equal to 3 , and the third term, a3, is equal to 192 . Which number represents the common ratio of the geometric sequence?r=6r=7r=8r=9
Identify Given Terms: Identify the given terms in the geometric sequence. We are given the first term a1=3 and the third term a3=192. In a geometric sequence, each term after the first is found by multiplying the previous term by a constant called the common ratio (r).
Write Third Term Formula: Write the formula for the third term of a geometric sequence.The nth term of a geometric sequence can be found using the formula an=a1⋅rn−1. For the third term, the formula is a3=a1⋅r3−1=a1⋅r2.
Substitute Known Values: Substitute the known values into the formula.We know that a1=3 and a3=192, so we can substitute these values into the formula to find r2.192=3×r2
Solve for r2: Solve for r2.To find r2, we divide both sides of the equation by 3.r2=3192r2=64
Find Value of r: Find the value of r.Since r2=64, we take the square root of both sides to solve for r.r=64r=8 or r=−8
Determine Appropriate Value: Determine the appropriate value of r. In the context of a geometric sequence, the common ratio can be positive or negative. However, since we are given options for r and they are all positive, we choose r=8 as the common ratio.
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