Tinh S = 2^3 + 3^3 +4^3+5^3+...+20^3 . S=...
S=2^3+3^3+4^3+5^3................+20^3
Tinh S
Tinh S = 2^3+3^3+4^3+5^3+.....+20^3
tinh nhanh
S= -1-3-3^2-3^3-3^4-.....-3^20
cho s=1-3+3^2-3^3+....+3^98-3^99
a, cmr s la boi cua -20
b,tinh s roi suy ra 3^100 chia 4 du 1
cho S=1-3+3^2-3^3+...+3^98-3^99
a) chung minh rang S la boi cua -20
Tinh S tu do suy ra 3^100 chia cho 4 du 1
choS= 1-3+3^2-3^3+...+3^98-3^99
A,CMR S LA BOI CUA -20
B,TINH S TU DO SUY RA 3^100 CHIA 4 DU 1
Tinh tong S= 12+22+32+42+..............+202 - (1+2+3+...........+20)
S=
Tinh S:23+33+43+......203.
CAN GAP MIK SE TICK