Question

1) 1+2+3+...+49 =?


2) 2+4+6+...+98 =?

Ajutati-ma va rog!!

Answer 1

1+2+3+...+49=
=49×50:2=
=1225

2+4+6+...+98=
=2(1+2+3+...+49)=
=2×49×50:2=
=2×1225=
=2450

Answer 2

1.1+2+3+...+49 =1225

Folosim Suma lui Gauss
n(n+1)/2
49(49+1)/2
49*50/2
1225

2.2+4+6+...+98 =4900
Folosim Suma lui Gauss
2+4+6+...+98=
=2(1+2+3+...+49)=
=2×49×50/2=
=4900/2
=2450

sper ca te-am ajutat^^