Question

Compară numerele A= 2+4+6+.......+30 şi B= 1+3+5+.............+29


VĂ ROG URGENT DAY COROANĂ!!!

Answer 1

A=2+4+6+...+30=2(1+2+3+....+15)=2*15*16/2=15*16=240
B=1+3+5+...+29=(1+2+3+......+29)-(2+4+6+...+28)=
  =29*30/2-2(1+2+3+....+14)=29*15-2*14*15/2=435-14*15=435-210=225
240>225  A>B

Answer 2

A=2+4+6+...+30
A=30+...+6+4+2
--------------------------
2A=32+...+32+32
Numar termeni : (30-2)/2+1=28/2+1=14+1=15
2A=32x15
A=32x15/2
A=16x15
A=240

B= 1+3+5+...+29 
B= 29+...+5+3+1
------------------------------
2B=30+30+...+30
Numar termeni : (29-1)/2+1=28/2+1=14+1=15
2B=15x30
B=15x30/2
B=15x15
B=225

240>225 ⇒ (2+4+6+.......+30)>(1+3+5+.............+29) ⇒ A>B 

Sper ca te-am ajutat ! :)