Răspunsuri

2014-09-28T17:25:09+03:00
3=1x4-1
7=2x4-1
11=3x4-1
15=4x4-1
.....
43=4x11-1
___________(+)
3+7+11+15+....+43=4(1+2+3+4+...+11)-1x11
3+7+11+15+...+43=4x11x12/2-11
3+7+11+15+...+43=253
14 4 14
2014-09-28T17:29:57+03:00
3=1x4-1
7=2x4-1
11=3x4-1
15=4x4-1
.....
43=4x11-1
___________(+)
3+7+11+15+....+43=4(1+2+3+4+...+11)-1x11
3+7+11+15+...+43=4x11x12/2-11
3+7+11+15+...+43=253
253-3+7+11+15=217
8 4 8