Question

Resolver:

x+y = -2
y+z = 13
z+x = 21

indicando: x²

Answer 1

x+y=-2
y=-2-x

y+z=13
(-2-x)+z=13
-x+z=13+2
z-x=15

z+x=21
z=21-x
21-x-x=15
21-2x=15
-2x=15-21
-2x=-6
x=-6/-2=3

y=-5
x=3
z=18

x2=9