Ответ:
\[a_{1} = - 9,1;\ \ d = 6,7;\]
\[a_{2} = - 2,4;\text{\ a}_{3} = 4,3;\ a_{4} = 11;\]
\[a_{5} = 17,7;\ a_{6} = 24,4;\ \ a_{7} = 31,1.\]
\[a_{1} = - 9,1;\ \ d = 6,7;\]
\[a_{2} = - 2,4;\text{\ a}_{3} = 4,3;\ a_{4} = 11;\]
\[a_{5} = 17,7;\ a_{6} = 24,4;\ \ a_{7} = 31,1.\]