Question

equçao com duas incognitas X+Y=5
X-Y²=3

Answer 1

x+y=5→x=5-y
x-y2=3→ x-y²=-3
5-y-y²=-3
-y²-y+5=3
-y²-y+5-3=0
-y²-y+2=0
a= -1 b=-1 c=2
∆=b²-4.a.c
=-1²-4.(-1).2
=1-(-8)
=9

Y½=-b±√∆/2.a
Y½=1±√9/2.(-1)
Y½=1±3/-2
Y1=1+3/-2=4/-2=-2
Y2=1-3/-2=2/-2=-1