Question

4+8+12+16+...............+484 factor comun rezolvarea ex

Answer 1

4+8+12+16+.....+484=4x(1+2+3+4+...+121)=4x121x122:2=29524
folosim factor comun axb+axc=ax(b+c)
apo suma lui Gauss unde 1+2+3+,,,+n=nx(n+1):2

Answer 2

4+8+12+16+...+484=
=4 x 1+4 x 2+ 4x 3 +4 x 4+ ....+4 x 121=
=4 x (1+2+3+4+...+121)=
Folosim formula sumei lui Gauss: 1+2+...+n  =n(n+1):2
=4 x 121 x 122:2=
=484 x 122:2=
=59048:2=
=29524.