Question

Determine o vigésimo termo da p.a (1/4,
7/12

Answer 1

Resposta:

$Calcular~~r\\ \\ a_2-a_1=r\\ \\ {7\over12}-{1\over4}={7-3\over12}={4\over12}=~~simplificando~~{1\over3}\\ \\ a_{20}={7\over12}\\ \\ a_1={1\over4}\\ \\ r={1\over3}\\ \\ n=20\\ \\ termo~~geral\\ \\ a_n=a_1+(n-1)r\\ \\ a_{20}={1\over4}+(20-1)({1\over3})\\ \\ a_{20}={1\over4}+(19)({1\over3})\\ \\ a_{20}={1\over4}+{19\over3}$

$a_{20}={3+76\over12}\\ \\ a_{20}={79\over12}$

Answer 2

resolução!

r = a2 - a1

r = 7/12 - 1/4

r = 7 - 3/12

r = 4/12

r = 1/3

a20 = a1 + 19r

a20 = 1/4 + 19 * 1/3

a20 = 1/4 + 19/3

a20 = 3 + 76/12

a20 = 79/12