#### Answer

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

#### Work Step by Step

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