Question

Determinati numerele naturale a,b,c stiind că
A+b=90;b+c=110;a+c=100

Answer 1

+=plus
-=minus
*=inmultit
a+b=90
b+c=110
a+c=100
a+b+b+c+a+c=90+110+100
2a+2b+2c=300
2*(a+b+c)=300(impartim la 2)
a+b+c=150
90+c=150
c=150-90
c=60
60+a=100
a=100-60
a=40
40+b=90
b=90-40
b=50

Answer 2

{a+b=90                 inmultim -1
{b+c=110

{-a-b=-90
{b+c=110
-a-b+b+c=110-90
-a+c=20

{-a+c=20
{a+c=100
-a+a+c+c=100+20
2c=120
c=120/2
c=60

din a+c=100 rezulta a+60=100
a=100-60
a=40

din a+b=90 rezulta 40+b=90
b=90-40
b=50