Question

em uma P.A o 1° termo igual a razão a14=84.Calcule a1 e a razão

Answer 1

$a_n=a_1+(n-1)\cdot r$

$a_{14}=a_1+13r$

$a_1=r \ \ \ \ \ a_14=84$

$r+13r=84$

$14r=84$

$r=\dfrac{84}{14}$

$r=6$

$a_1=6$

$\text{PA}(6,12,18,24,30,36,42,48,54,60,66,72,78,84)$