Question

numa pa de 100 metro, a50 + a51=10 calcule 5100

Answer 1

a50+a51=10 
a1+49r+a1+50r=10 
2a1+99r=10 

S100=(a1+a100).100/2 
S100=(a1+a1+99r).50 
S100=(2a1+99r).50 
S100=10.50 
S100=500.