Question

resolva os sistemas de equações.
a)x+y=9
x-y=7
b)3x-y=4
x+y=2
c)x=3+2y
3x-y=4
d)x+2(y-4)=7
4(x+1)+y=29

Answer 1

a)
x+y=9
x-y=7

2x=16
x=16/2

x=8
y=1

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

4x=6
x=6/4

x=1,5
y=0,5

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

3(3+2y)-y=4
9+6y-y=4
5y=4-9
5y=-5
y=-5/5

y=-1
x=1

d)
x+2(y-4)=7
4(x+1)+y=29

x+2y-8=7
4x+4+y=29

x+2y=7+8
4x+y=29-4

x+2y=15
4x+y=25 (-2)

x+2y=15
-8x-2y=-50

-7x=-35
x=-35/-7

x=5
y=5