Saturday, January 10, 2015

What are x,y and z? x+y=-3 x+z=-2 xy+yz+xz=2

First, we'll multiply the 1st and the 2nd
equations:


(x+y)(x+z) =
(-3)*(-2)


We'll remove the
brackets:


x^2 + xz + xy + yz =
6


We notice that the sum xz + xy + yz can be replaced by
the 3rd equation:


x^2 + 2=
6


x^2 = 6-2


x^2 =
4


x1 = 2 and x2 = -2


We'll
substitute x1 in the 1st equation:


2 + y =
-3


y = -2-3


y =
-5


We'll substitute x1 in the 2nd
equation:


2  +z = -2


z =
-4


We'll substitute x2 in the 1st
equation:


-2 + y = -3


y =
-1


We'll substitute x2 in the 2nd
equation:


-2 + z = -2


z =
0


The pairs of solutions are: (2 ; -5 ; -4)
and (-2  ;-1 ; 0).

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