Question

Tính tổng

A) A= 1+2+3+...+100

B) B= 2+4+6+...+120

C) A= 3+5+8+...+99

D) B= 3+6+9+...123

Answer 1

A=[(99-3):3+1].(99+3):2=33.102:2=33.51=1683

Answer 2

C=[(99-3):3+1].(99+3):2=33.102:2=33.51=1683

B=[(120-2):2+1].(120+2):2=60.122:2=60.61=3660

A=[(100-1):1+1].(100+1):2=100.101:2=50.101=5050

D=[(123-3):3+1].(123+3):2=41.126:2=41.63=2583

 

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