Răspuns:
Explicație pas cu pas:
f(0)=2*0+1 = 1
f(1)=2*1+1=3
f(2)=2*2+1=5
........
f(10)=2*10+1=21
Deci A=1+3+5+...+21 = [tex]\frac{(1+21)*11}{2} =\frac{22*11}{2}=11*11=11^{2}[/tex]
