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x+y=-7; y+z=1
calculeaza:2x+5y+3z-7=?


Răspuns :

2x+5y+3z-7 = 2x+2x+3y+3z-7 = 2(x+y)+3(y+z)-7 = 2*(-7) + 3*1 -7 = -14+3-7 =-21+3 = -18
2x+5y+3z-7 = 2x+2x+3y+3z-7 = 2(x+y)+3(y+z)-7 = 2×(-7) + 3×1 -7 = -14+3-7 =-21+3 = -18