Question

am nevoie de toate sa fie rezolvate va rooog​

Answer 1

Răspuns:

1. a) din x+y=2   scoatem x= 2-y si inlocuim in a 2 ecuatie

3*(2-y)+2y=3   6-3y+2y=3    6-3=y   y=3

x= 2-3=-1   x=-1

b) -x+y=4  scoatem x=y-4 inlocuim in a 2 ecuatie

5y-20+2y=8   7y=28   y=4

x=4-4=0   x=0  (pe urmatoarele le faci dupa model)

2. a) $\left \{ {{x+y=5} \atop {x-y=1}} \right.$    se aduna ecuatiile

x+y+x-y=5+1    2x=6  => x=3

y=x-1= 3-1=2   y=2

b) $\left \{ {{x+y=4} \atop {2x-y=-1}} \right.$   se aduna ecuatiile

x+y+2x-y=4-1    3x=3  => x=1

y=4-x=4-1=3   y=3   (dupa model le faci)

3. a) $\left \{ {{x+2y=-1} \atop {4x-2y=6}} \right.$    se aduna ecuatiile

x+2y+4x-2y= 6-1     5x=5  => x=1

2y=-1-x =-1-1=-2    y=-2: 2= -1   y=-1

b) $\left \{ {{3x+4y=6} \atop {x-4y=-14}} \right.$   se aduna ecuatiile

3x+4y+x-4y= 6-14    4x= -8   x= -8:4= -2    x=-2

4y=6-3x= 6+6=12   y=12:4 =3   y=3