Dik:25,29,33,…,189 dit: suku ke berapakah 189?

Aritmatika.

25,29,33,…,189
Diperoleh a= 25, b=4
Un= 189
n= ••••?
Un = a+(n-1)b
189 = 25+ nb – b
189 = 25 +4n – 4
4n = 189 – 21
4n = 168
n = 168/4
n = 42 ✔
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