Question

Determine a P.A cujo sexto termo é 10 e o décimo segundo termo é 20?

Answer 1

Boa tarde!

Dados:

a1 → ?

an → 20

N → 12

r → ?

_______________

Tf-Ti → 12-6 = 6

Vf-Vi → 20-10 = 10

R → 10/6 → 5/3

_______________

An=a1+(n-1)·r

20=a1+(12-1)·5/3

20=a1+11·5/3

20=a1+55/3

20-a1=55/3

-a1=55/3-20

-a1=-5/3 (-1)

a1=5/3

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P.A: (5/3, 10/3, 5, 20/3, 25/3, 10, 35/3, 40/3, 15, 50/3, 55/3, 20)

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Att;Guilherme Lima