[tex]x * y=x y+x+y-2[/tex]
a)
Inlocuim pe x cu -1 si pe y cu 2020 si obtinem:
-1*2020=-2020-1+2020-2=-3
b)
x*(2x)=3
2x²+x+2x-2=3
2x²+3x-5=0
Δ=9+40=49
[tex]x_1=\frac{-3+7}{4} =1\\\\x_2=\frac{-3-7}{4} =-\frac{5}{2}[/tex]
c)
m*n=mn+m+n-2
mn+m+n-2=-1
mn+m+n-1=0
m(n+1)+n+1-2=0
(n+1)(m+1)=2
n+1=1 si m+1=2
n=0 si m=1
n+1=2 si m+1=1
n=1 si m=0
Un alt exercitiu cu legi de compozitie gasesti aici: https://brainly.ro/tema/9918952
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