Chapter 11 - Further Topics in Algebra - 11.1 Sequences and Series - 11.1 Exercises - Page 1014: 14

$a_{1}=\dfrac {7}{6};a_{2}=\dfrac {5}{4};a_{3}=\dfrac {4}{3};a_{4}=\dfrac {3}{2};a_{5}=2$

$a_{1}=\dfrac {1-7}{1-6}=\dfrac {-7}{-6}=\dfrac {7}{6};$ $a_{2}=\dfrac {2-7}{2-6}=\dfrac {5}{4};$ $a_{3}=\dfrac {3-7}{3-6}=\dfrac {4}{3};$ $a_{4}=\dfrac {4-7}{4-6}=\dfrac {3}{2};$ $a_{5}=\dfrac {5-7}{5-6}=2$