Q. Find an explicit formula for the geometric sequence 12,24,48,96 where the first term should be b(1)
Identify Terms: Identify the first term b(1) and the common ratio r of the geometric sequence.The first term b(1) is 12.To find the common ratio, divide the second term by the first term: r=1224=2.
Calculate Common Ratio: Use the formula for the nth term of a geometric sequence, which is b(n)=b(1)⋅r(n−1), where b(n) is the nth term, b(1) is the first term, and r is the common ratio.Substitute the values of b(1)=12 and r=2 into the formula to get b(n)=12⋅2(n−1).
Use nth Term Formula: Check the formula with the given terms of the sequence to ensure it is correct.For n=1, b(1)=12×2(1−1)=12×20=12×1=12, which matches the first term.For n=2, b(2)=12×2(2−1)=12×21=12×2=24, which matches the second term.For n=3, b(3)=12×2(3−1)=12×22=12×4=48, which matches the third term.For n=4, b(4)=12×2(4−1)=12×23=12×8=96, which matches the fourth term.The formula is verified with the given terms.