12 + 14 + 16 + 18 + 20 + ... + 50 + 52 + 54 + 56 + 58
= ( 12 + 58 ) + ( 14 + 56 ) + ... + ( 34 + 36 )
= 70 + 70 + ... + 70
= 70 x 12
= 840
~ Hok tốt ~
=(12+58)+(14+56)+(16+54)+....+(30+30)
= 60 + 60 + 60 +.....+ 60
= 60 x 12
= 720
Hok tốt nha
12 + 14 + 16 + 18 + 20 + ... + 50 + 52 + 54 + 56 + 58
= ( 12 + 58 ) + ( 14 + 56 ) + ... + ( 34 + 36 )
= 70 + 70 + ... + 70
= 70 x 12
= 840
Study well ! >_<
12 + 14 + 16 + 18 + 20 + ... + 50 + 52 + 54 + 56 + 58
= ( 12 + 58 ) + ( 14 + 56 ) + ... + ( 34 + 36 )
= 70 + 70 + ... + 70
= 70 x 12
= 840
Study well ! >_<