Question

2) Determine o valor numérico do 13º termo da progressão
aritmética (2, a-b, a-b+7,...).

Answer 1

$\Large\boxed{\begin{array}{l}\sf(2,a-b,a-b+7,...)\\\sf r=a-b+7-(a-b)\\\sf r=\diagup\!\!\!a-\diagup\!\!\!b+7-\diagup\!\!\!a+\diagup\!\!\!b\\\sf r=7\\\sf a_{13}=a_1+12r\\\sf a_{13}=2+12\cdot7\\\sf a_{13}=2+84\\\sf a_{13}=86\end{array}}$