Question

Fie progresia aritmetica (bn)n )_>1 in care b1=1 si b2=3 . Calculati b4

Answer 1

b2= b1+ r => r= b2-b1= 2
b3= b2+r= 3+2=5
deci b4= b3+r= 5+2=7

Answer 2

Ratia o notam cu r

Astfel r = b₂ - b₁ ⇒ r = 3-1 ⇒ r =2

b₄ = b₁+ 3 r ⇒ b₄ = 1 + 3 · 2 ⇒ b₄ =7