Question

ajutorrrr! calculează 1+2 +3 +4 +.... +100= 2+4+6+8+....+100= 1+3+5+....+99=

Answer 1

1+2+3+4+...+100
Sunt 100 de termeni
Suma :(1+100)·100:2=101·100:2=101·50=5050

2+4+6+8+...+100
Sunt (100-2):2+1=98:2+1=49+1=50 termeni
Suma: (2+100)·50:2=102·50:2=51·50=2550

1+3+5+...+99
Sunt (99-1):2+1=98:2+1=49+1=50 termeni
Suma :(1+99)·50:2=100·50:2=100·25=2500

Answer 2

1+2+3+4+....+100=
S=(100+1)×100÷2
S=101×50
2+4+6+8+...100=
S=(100+2)×50÷2
S=102×25
S=2550
1+3+5+...+99
S= (99+1)×3÷2
S=100×3÷2
S=50×3
S=150