Question

Va rog vreau explicarea a 3 necunoscute shtiind ca x+y+z=500 shi 30x+10y+1z=100 dau coroana

Answer 1

x+y+z=500
30x+10y+1z=100 <=> 30x +10y + 1*z=100
                                    30x+ 10y+  z =100 => z=100-30x-10y
 
x+y+z=500 => z=500-x-y

100-30x-10y=500-x-y

100=30x+10y
500=x+y  |* (-10)

100=30x+10y
-5000= -10x -10y
.............................
-4900= 20x + /

x= -4900/20

x= -245

x+y=500  => y=500-x= 500-(-245)= 500+245= 745

y=745

z=500-x-y= 500-745-(-245)= 500-745+245= 745-745=0

z=0