TÍNH TỔNGS =1.C22020+2.C32020+3.C42020+· · ·+2019.C20202020.A....
Câu 46. Tính tổngS =1.C
2
2020
+2.C3
2020
+3.C4
2020
+· · ·+2019.C2020
2020
.A.S = 2018.22019
+1 B.S =2020.22019
−1C.S = 2018.22019
+2018 D.S =2018.22019
−1u1
= √2019