Answers

2016-05-12T19:16:56+08:00
To get a₉, a₂₉, a₄₂,find the common difference.
formula: d=a₂-a₁ --------> you can use any consecutive nth number like a₃-a₂. You will get the same result.
d=a₂-a₁
d=12-5
d=7

check: 5+7=12, 12+7=19, 19+7=26 and 26+7=33. Our common difference is correct.

To find the other term, use the nth number formula:
a<sub>n = a
+(n-1)(d)

Find a₉:
a₉=5+(9-1)(7)
a₉=5+(8)(7)

a₉=5+56
a₉=61

Our 9th term or a₉ is 61.

find a₂₉:
a₂₉=5+(29-1)(7)
a₂₉=5+(28)(7)
a₂₉=5+196
a₂₉=201

Our 29th term or a₂₉ is 201.

find a₄₂:
a₄₂=5+(42-1)(7)
a₄₂=5+(41)(7)
a₄₂=5+287
a₄₂=292

Our 42nd term or a₄₂ is 292.

Answers: a₉=61, a₂₉=201, a₄₂=292
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