Question

Resolva as seguintes equações:
A)X+Y=5
2X-Y=7

B)X+Y=7
X-Y=3

Answer 1

1-
x= 5-y

2×(5-y)-y= 7
10-2y-y= 7
-3y= -7-10
-3y= -3 .(-1)
y= 3/3
y= 1

x= 5-y
x= 5-1
x= 4

2-

x= 7-y

(7-y)-y= 3
-2y= 3-7
-2y= -4 . (-1)
y= 4/2
y= 2

x= 7-y
x= 7-2
x= 5