Question

Please help me with this ​

Answer 1

Seems like I've done a few of these already today.

1.

a[1] = 4, d=6

Formula: a[n] = 4 + 6(n-1)

a[40]=4 + 6(39) = 238

Table: 4 10 16 22 28 34   ...   a[40]=238

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2.

a[23]=25, d=3

a[n] = a[1] + d(n-1)

25=a[23]=a[1] + 3(22)

a[1] = 25 - 66 = -41

Table: -41 -38 -35 -32 -29 -26

Let's check a[23]= -41 + 3(22)= 25, good

Formula: a[n] = -41 + 3(n-1)