Question

f 2 + 4 + 6 + ... +100=
1+ 3 + 5 + ...
+ 99 =​

Answer 1

(2+4+6+.......+100) + (-1-3-5-.......-99)= 2550-2500=50

2(1+2+3+...+50)=2×50×51/2=2550

(-1-3-5-.......-99)=

nr termeni (99-1):2+1=98:2+1=50 termeni  

se grupeaza cate 2    -1-99=-100  ; -3-97=-100  

-1-3-5-.....-99= (-1-99)+(-3-97).....(-49-51) =-100×25=-2500

sper ca te-am ajutat ;)