ГДЗ по алгебре 9 класс Макарычев Задание 575

 

\[\boxed{\text{575}\text{\ (575)}\text{.}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[\textbf{а)}\ a_{n} = a_{1} + 4 \cdot (n - 1)\]

\[a_{1} = 10\]

\[a_{2} = 10 + 4 \cdot 1 = 14\]

\[a_{3} = 10 + 4 \cdot (3 - 1) = 10 + 8 =\]

\[= 18\]

\[a_{4} = 10 + 4 \cdot (4 - 1) = 22\]

\[a_{5} = 10 + 4 \cdot (5 - 1) =\]

\[= 10 + 16 = 26.\]

\[\textbf{б)}\ a_{n} = 30 - 10 \cdot (n - 1)\]

\[a_{1} = 30\]

\[a_{2} = 30 - 10 = 20\]

\[a_{3} = 30 - 10 \cdot 2 = 10\]

\[a_{4} = 30 - 10 \cdot 3 = 0\]

\[a_{5} = 30 - 10 \cdot 4 = - 10.\]

\[\textbf{в)}\ a_{n} = 1,7 - 0,2 \cdot (n - 1)\]

\[a_{1} = 1,7\]

\[a_{2} = 1,7 - 0,2 = 1,5\]

\[a_{3} = 1,7 - 0,2 \cdot 2 = 1,7 - 0,4 =\]

\[= 1,3\]

\[a_{4} = 1,7 - 0,2 \cdot 3 = 1,1\]

\[a_{5} = 1,7 - 0,2 \cdot 4 = 1,7 - 0,8 =\]

\[= 0,9.\]

\[\textbf{г)}\ a_{n} = - 3,5 + 0,6 \cdot (n - 1)\]

\[a_{1} = - 3,5\ \]

\[a_{2} = - 3,5 + 0,6 = - 2,9\]

\[a_{3} = - 3,5 + 0,6 \cdot 2 = - 2,3\]

\[a_{4} = - 3,5 + 0,6 \cdot 3 =\]

\[= - 3,5 + 1,8 = - 1,7\]

\[a_{5} = - 3,5 + 0,6 \cdot 4 =\]

\[= - 3,5 + 2,4 = - 1,1.\]

\[\boxed{\text{575.}\text{\ }\text{ОК\ ГДЗ\ -\ домашка\ на\ 5}}\]

\[\textbf{а)}\ x_{1} = 1,\ x_{2} = 2,\ \ldots,\ x_{150} = 150;\]

\[S_{150} = \frac{\left( x_{1} + x_{n} \right)}{2} \cdot n =\]

\[= \frac{1 + 150}{2} \cdot 150 = 11\ 325;\ \]

\[\textbf{б)}\ x_{1} = 20,\ \ x_{2} = 21,\]

\[\text{\ \ }x_{n} = 19 + n,\ \ x_{n} = 120;\]

\[19 + n = 120,\ \ n = 101,\]

\[S_{101} = \frac{\left( x_{1} + x_{n} \right)}{2} \cdot n =\]

\[= \frac{20 + 120}{2} \cdot 101 = 7070;\]

\[\textbf{в)}\ x_{1} = 4,\ \ x_{2} = 8,\]

\[\text{\ \ }x_{n} = 4n,\ \ x_{n} = 300,\ \ \]

\[300 = 4n,\ \ n = 75,\]

\[S_{75} = \frac{\left( x_{1} + x_{n} \right)}{2} \cdot n =\]

\[= \frac{4 + 300}{2} \cdot 75 = 11\ 400;\]

\[\textbf{г)}\ x_{1} = 7,\ \ x_{2} = 14,\]

\[\text{\ \ }x_{n} = 7n,\ \ 7n \leq 130,\]

\[\ \ n \leq 18\frac{4}{7};\]

\[n = 18,\ \ x_{n} = 126,\]

\[\text{\ \ }S_{18} = \frac{7 + 126}{2} \cdot 18 = 1197.\]