cmr:1)A=45^2020+45^2021 $\vdots$ 46
2)B=20^2020-20^198 $\vdots$
3)C=n^2(n=1)+2n(n+1) $\vdots$ 6
4)D=(n+3)62-(n-1)^2 $\vdots$ 8
Loga
Sinh Học lớp 12
