Question

Rezolvati inmultimea numerelor reale sistemul de ecuatii
a) {x-y=0
5x+y=1
b) {4x-y=1
8x-2y=3
c) {2x+3y=1
2x-5y=9

Answer 1

a)
 x-y=0
5x+y=1

x=y
5y+y=1

x=y
6y=1

x=1/6
y=1/6

b)
4x-y=1
8x-2y=3

y=4x-1
8x-2(4x-1)=3

y=4x-1
8x-8x+1=3

y=4x-1
1=3

In sistemul acesta, cred ca in enunt este o greseala undeva

c)
2x+3y=1
2x-5y=9

2x=1-3y
1-3y-5y=9

2x=1-3y
-8y=9-1

2x=1-3y
-8y=8

2x=1-3y
y=-1

2x=1-3*(-1)
y=-1

2x=1+3
y=-1

2x=4
y=-1

x=2
y=-1