ГДЗ по алгебре 9 класс Макарычев Задание 606

\[\boxed{\text{606\ (}\text{с}\text{).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

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

\[\textbf{а)}\ x_{n} = 4n + 2,\ \ x_{1} = 4 + 2 = 6,\ \]

\[S_{n} = \frac{(4n + 2 + 6)}{2} \cdot n = 2n^{2} + 4n,\]

\[S_{50} = 2 \cdot 50^{2} + 4 \cdot 50 = 5200;\]

\[S_{100} = 2 \cdot 100^{2} + 4 \cdot 100 = 20\ 400.\]

\[\textbf{б)}\ x_{n} = 2n + 3,\ \ x_{1} = 2 + 3 = 5,\ \]

\[S_{n} = \frac{(5 + 2n + 3)}{2} \cdot n = n^{2} + 4n;\]

\[S_{50} = 2500 + 200 = 2700;\]

\[S_{100} = 100² + 4 \cdot 100 = 10\ 400.\]