Question

S=2+4+6+........100=

Answer 1

S=2+4+6+........100
pui un 2 factor comun si ai

2(1+2+3+...+50)=
rezolvam paranteza cu gaus

50(50+1)/2=50*51/2= 25*51 = 1275


2(1+2+3+...+50)= 2 *1275 = 2550

Answer 2

S=2+4+6+...+100=2 x(1+2+3+..+50)=2 x 50x(50+1) :2=2 cu 2 se simplifica si ne da ca 50x51=2550