中等MATH-EXPL-006
A geometric sequence has first term 5 and common ratio 2. What is the 6th term?
A. 160✓ 答案
B. 320
C. 64
D. 80
解說
T_6 = 5 × 2^(5) = 5 × 32 = 160. The exponent is n − 1, so 5 × 2^6 = 320 is one step too far.
T_6 = 5 × 2^(5) = 5 × 32 = 160. The exponent is n − 1, so 5 × 2^6 = 320 is one step too far.