B. The Geometric Mean Between The First Two Terms In A Geometric Sequence Is 32. If The 3rd Term Is 4, Find The First Term
B. The geometric mean between the first two terms in a geometric sequence is 32. If the 3rd term is 4, find the first term
Answer:
64
Step-by-step explanation:
B. The geometric mean between the first two terms in a geometric sequence is 32. If the 3rd term is 4, find the first term
Given: Geometric mean (first 2 terms) = 32
3rd term (a3)= 4
Required: first term
Geometric mean (GM)
GM = nth root of (a1 × a2 × a3 × an)
n = 2
a1 = 1st term
a2 = 2nd term
a2 / a1 = a3 / a2
(a2)² = (a1)(a3)
a2 = √(a1)(a3)
GM = √a1 × √(a1 × a3)
32 = √a1 × √(a1 × 4)
solve for a1
a1 = 64
a2 = √(64 × 4)
a2 = 16
16/64 = 4 /16 ??
1/4 = 1/4 Therefore it is correct
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