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am nevoie de ajutor va rog!!!!!!!!!!!!!!!!!!!!!!!!!!!
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Răspuns:
B) 650
Explicație pas cu pas:
B) ( 4+8+12+16+...+100) :(2+4+6+....+50)=
=4(1+2+3+....+25) :2(1+2+3+....+25)
=(1+2+3....+25) *(4:2)=
=[(25(25+1)]/2 *2=
=25*26=650
D) (6+12+18+...+300)°3:(3+6+9+....+150)=
=6°3(1+2+3+...+50)°3: 3(1+2+3+....+50)=
(1+2+3+...+50)*[6°3(1+2+3+...+50)°2 : 3]=
[50(50+1)]/2 *{216 *[50(50+1)]/2°2:3}=
(50*51)/2 * [216*(5*51)/2°2 :3]=
=2550/2 *