Question

numa P.A termo = 13 e a razão = 4 calcule o vigésimo quinto termo​

Answer 1

$a_1=13;\;r=4;\;a_{25}=\,?$

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

$a_{25}=13+(25-1)\cdot4$

$a_{25}=13+24\cdot4$

$a_{25}=13+ 96$

$\red{\boldsymbol{ a_{25}= 109}}$