Q. Find the 8th term of the geometric sequence 5,20,80,…Answer:
Identify type of sequence: Identify the type of sequence.The given sequence is geometric because each term after the first is found by multiplying the previous term by a constant ratio.
Determine common ratio: Determine the common ratio r of the sequence.To find the common ratio, divide the second term by the first term.r=520=4
Use formula for nth term: Use the formula for the nth term of a geometric sequence.The nth term Tn of a geometric sequence can be found using the formula Tn=a⋅r(n−1), where a is the first term and n is the term number.
Calculate 8th term: Calculate the 8th term using the formula. T8=5×48−1=5×47
Perform exponentiation: Perform the exponentiation. 47=4×4×4×4×4×4×4=16384
Multiply by first term: Multiply the result by the first term.T8=5×16384=81920