Question

Considere a PA (5,10...90) ache a20 e a30

Answer 1

A1=5

An=20 e 30

r=5

An=a1+(n-1).r

A20=5+(20-1).5

A20=5+19.5

A20=5+95

A20=100

An=a1+(n-1).r

A30=5+(30-1).5

A30=5+29.5

A30=5+145

A30=150