Question

3х + y + z = 1
x+3y+z=2
3x-5y+2z=-7​

Answer 1

a) 3(x+y) -1 = 3 ×(-7) -1 = -22

b) din x+y = -7

  si    y+z = 1

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adunam ecuatiile :

⇒  x+2y +z = -6

c) 2x +5y +3z -7 = 2x + 2y + 3y + 3z -7 = 2(x+y) +3(y+z) -7 = 2× (-7) +3 ×1 -7

= -14 +3 -7 = -18