Question

demonstrati ca sumele urmatoare sunt patrate perfecte 1+3+5. 1+3+5+7+9+11+13+15. 1+3+5+7. 1+3+5+....+99va roooogggggg mult acum

Answer 1

a.1+3+5=9 adica 3x3=3²

b.(2*0+1)+(2*1+1)+(2*2+1)...+(2*7+1)=

2(1+2+..+7)+1+1+..+1(de 8 ori)=

2*7*8/2+8=

7*8+8=

8(7+1)= 8*8 !!!

c.(2*0+1)+(2*1+1)+...+(2*49+1)=

2(1+2+..+49)+50=

2*49*50/2+50=

50(49+1)=50*50 !!!