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the value of the 8th term is 78 the sequence is increasing by 10 each time. find the 20th term

Respuesta :

nobillionaireNobley
an = a + (n - 1)d
a8 = a + (8 - 1) x 10 = a + 7 x 10 = a + 70
a + 70 = 78
a = 78 - 70 = 8

20th term (a20) = 8 + (20 - 1) x 10 = 8 + 19 x 10 = 8 + 190 = 198

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