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Efectuati ,utilizand formule de calcul prescurtat:
a.(x+y-z)(x+y+z)=
b.(x-y-z)(x+y+z)=
c.(x+y+z)(x-y+z)=
d.(y+z-x)(y-z+x)=
e.(4x+2y +z)la a doua (2)=
f.(3x-y-z) la a doua =