Question

Determine o centésimo nono termo da PA, sendo que a12=2/5 e a r=3/5

Answer 1

an = ak + ( n - k ).r

2/5 = a109 + ( 12 - 109 ) . 3/5
2/5 = a109 + (-97 ) . 3/5 
2/5 = a109 - 291/5
2/5 + 291/5 = a109
a109 = 293/5