Question

Numa P.A , Sabe-se que a8 = 15 e a1= 1 . determine a razão.

Answer 1

$\mathsf{a_{8}=a_{1}+7r}\\\mathsf{15=1+7r}\\\mathsf{7r=15-1}\\\mathsf{7r=14}$

$\mathsf{r=\dfrac{14}{7}}\\\boxed{\boxed{\boxed{\boxed{\mathsf{r=2}}}}}$

Answer 2

resolução!

a8 = a1 + 7r

15 = 1 + 7r

15 - 1 = 7r

14 = 7r

r = 14/7

r = 2