Question

calcule o termo 20 graus (26,31,36,41)

Answer 1

Trata-se de determinar o vigésimo termo de uma PA onde
a1 = 26 
r = 5

Use a fórmula do termo geral das PAs:

$a_n=a_1+(n-1)r\\ \\ a_{20}=26+(20-1)5\\ \\ a_{20}=26+19*5\\ \\ a_{20}=26+95\\ \\ \boxed{a_{20}=121}$

Answer 2

$(26,31,36,41,\dots)$

$r=a_2-a_1$

$r=31-26~~\Rightarrow~~r=5$

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

$a_{20}=a_1+19r$

$a_{20}=26+19\cdot5~~\Rightarrow~~a_{20}=26+95$

$\boxde{a_{20}=121}$