Question

equacão do segundo grau

x+y=25
2x+3y= 55

2+y=4
2x-3y=3

x+y=10
x-y=6

Answer 1

A)

x+y=25
2x-3y=55

x=25-y
2(25-y)-3y=55

50-2y-3y=55
-5y=55-50
-5y=5  (-1)  Nunca a incógnita será negativa.
y=-5/5
y=1

x+y=25
x+(-1)=25
x=25+1
x=26


B)

2+y=4
2x-3y=3

y=4-2
y=2

2x-3y=3
2x-3*2=3
2x-6=3
2x=3+6
2x=9
x=9/2

C)

x+y=10
x-y=6

2x=16
x=16/2
x=8

x-y=6
8-y=6
-y=6-8
-y=-2  (-1)
y=2