Question

NA P.A EM QUE A1=28 E A8=84 CALCULE A RAZÃO

Answer 1

$a_1=28\\a_8=84\\n=8\\r=?\\\\\\a_n=a_1+(n-1)\times r\\\\\\ 84=28+(8-1)\times r\to\\\\ 84=28+7r\to\\\\ 84-28=7r\to\\\\ 56=7r\to\\\\ \dfrac{56}{7} =r\to\\\\ \large\boxed{r=8}\\\\\\\\ PA~(28, 36, 44, 52, 60, 68, 76, 84)$

Answer 2

$a_{n} = a_{1} +(n-1).r \\ \\ a_{8} =84 \\ \\ a_{1} =28 \\ \\ r=? \\ \\ a_{8} = a_{1} +(8-1).r \\ \\ 84=28+7r \\ \\ 84-28=7r \\ \\ 56=7r \\ \\ r= \frac{56}{7} =8$

A razão é igual a 8