Question

The 7th term of 1/3,1/7,1/11,....is
a)27
b)0
c)7/3
d)1/27​

Answer 1

$a = \frac{1}{3} \\ d = \frac{1}{7} - \frac{1}{3} \\ = \frac{3 - 7}{21} \\ = \frac{ - 4}{21} \\ n = 7 \\ an = ? \\ an = a + (n - 1)d \\ an \\ = \frac{1}{3} + (7 - 1)( \frac{ - 4}{21} ) \\ = \frac{1}{3} + 6 \times ( \frac{ - 4}{21} ) \\ = \frac{1}{3} - \frac{24}{21} \\ = \frac{7 - 24}{21} \\ = \frac{ - 17}{21} \\ hence \: the \: 7th \: term \: is \: \frac{ - 17}{21} .$