Explicație pas cu pas:
a) x-2y=-1
2x-y=7
Metoda(1)
x-2y=-1 => x=-1+2y=-1+2×3=-1+6=5
2x-y=7. 2(-1+2y)-y=7=>-2+4y-y=7=>-2+3y=7=>3y=7+2=9/:(+3)=>y=3
b)4x-3y=20/×(+6) Metoda(2).
5x+2y=2/×(+9)
24x-18y=120(+)
45x+18y=18
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69x=138/÷(+69)
x=2
2×4-3y=20=>8-3y=20=>-3y=20-8=12/÷(-3)=>y=-4
Baftă !!!!!!!
