Question

Va rog cat mai repede! Rs corect!

Answer 1

$(-1)^{10} =+1$

$(-1)^{11} =-1$,

....................................

$(-1)^{19} =-1$

$(-1)^{20} =+1.$

iar sirul devine: +1-1+1-1+1-1+1-1+1-1+1=-5+6=1.