Question

Помогитеее с решением прошу!!!

Answer 1

$19)x_{n}=\frac{2\sqrt{3}-5n }{3}\\\\x_{1}=\frac{2\sqrt{3}-5*1 }{3}=\frac{2\sqrt{3}-5 }{3}\\\\x_{2}=\frac{2\sqrt{3}-5*2 }{3}=\frac{2\sqrt{3}-10 }{3}\\\\d=x_{2}-x_{1}=\frac{2\sqrt{3}-10 }{3} -\frac{2\sqrt{3}-5 }{3}=\frac{2\sqrt{3}-10-2\sqrt{3}+5}{3} =-\frac{5}{3}=\boxed{-1\frac{2}{3}}$

Нет правильного ответа

$20)b_{n} =3,5*(\sqrt{2})^{n-2} \\\\3,5*(\sqrt{2})^{n-2}>14\\\\(\sqrt{2})^{n-2}>4\\\\(2^{\frac{1}{2}})^{n-2}>4\\\\2^{0,5n-1}>2^{2}\\\\0,5n-1>2\\\\0,5n>3\\\\n>6\\\\Otvet:\boxed{n=7}$