PLEASE HELP!! I WILL GIVE BRAINLIEST!! I don’t understand please help with number 15 & 16

Mathematics

1 answer:

olga55 [171]2 years ago

6 0

Answer:

Step-by-step explanation:

15) t = 1 , 3t - 2 = 3*1 - 2 = 3 - 2 = 1

t =2, 3t - 2 = 3*2 - 2 = 6 -2 = 4

t = 3, 3t - 2 = 3*3 - 2 = 9 - 2 = 7

t = 4 , 3t - 2 = 3*4 - 2 = 12 - 2 = 10

Series : 1,4,7,10,.........

a = first term = 1

d = common difference = 2nd term - first term = 4 - 1 = 3

n = number of terms = 20

S = $\frac{n}{2}*(2a + (n-1)d)$

$=\frac{20}{2}(2*1 +19*3)\\\\= 10 * (2 + 57)\\\\= 10* 59\\\\= 590$

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