Răspuns:
Explicație pas cu pas:
a)substitutie
2x+y=3 2(-1-2y)+y=3 -2 -4y+y=3 -3y=1 y=-1/3
x+2y=-1 x=-1-2y x=-1+2/3=-1/3 x=-1/3
reducere
2x+y=3 2x+y=3
x+2y=-1 (-2) -2x-4y=-2
..................
-3y=1 y=-1/3 x=-1+2/3=-1/3
b)reducere
3x+2y=6 (-2) -6x-4y=-12
2x+3y=5 (3) 6x+9y=15
........................
5y=3 y=3/5 2x+9/5=5 10x=25-9 x=8/5
substitutie
y=(6-3x)/2
2x+3(6-3x)/2=5 4x+18-9x=10 -5x=-8 x=8/5
y= 3(2-8/5)/2=3/10×(10-8)=3×2/10=3/5 y=3/5
..............
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