Question

1. Rezolvati prin metoda reducerii urmatoarele sisteme:
a)
{x+2y=2
{x-y=4

b)
{x-y=4
{x+2y=1

c)
{x+2y=9
{x-y=-1

d)
{2x-y=0
{x+2y=2

Answer 1

a)
{x+2y=2
{x-y=4

x=4+y
4+y+2y=2
3y=-2
y=-2/3
x=4-2/3=10/3

b)
{x-y=4         
{x+2y=1

x=4+y
4+y+2y=1
3y=-3
y=-1
x=4-1=3

c)
{x+2y=9
{x-y=-1

x=y-1
y-1+2y=9
3y=10
y=10/3
x=10/3-1=7/3

d)
{2x-y=0
{x+2y=2

y=2x
x+4x=2
5x=2
x=2/5
y=4/5