Question

найдите S6 a1=3√2. q=√2​

Answer 1

Объяснение:

$a_1=3\sqrt{2} \ \ \ \ q=\sqrt{2}\ \ \ \ S_6=?\\S_6= 3\sqrt{2}*\frac{(\sqrt{2})^6-1 }{\sqrt{2}-1 }=3\sqrt{2}*\frac{8-1}{\sqrt{2}-1 }=\frac{21\sqrt{2} }{\sqrt{2}-1 } = \frac{21\sqrt{2}*(\sqrt{2}+1) }{(\sqrt{2}-1)*(\sqrt{2}+1) } =\\=\frac{21*2+21\sqrt{2} }{2-1}=42+21\sqrt{2}.$

Ответ: S₆=42+21√2.