Practice question · Numerical answer
A geometric sequence has first term 5 and common ratio 3. Find the sixth term.
Hints
- Use a_n = a_1 times r to the power n - 1.
- 3 to the fifth power is 243.
Show the answer
1215
Why
a_6 = 5 x 3 to the fifth = 5 x 243 = 1215. Again the exponent is n - 1: the first term has been multiplied by r zero times. Writing 5 x 3 to the sixth would give 3645, the same off-by-one error in multiplicative dress.
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