Question

* calcule os sistemas abaixo pelos metodos da adiçao e substituiçao. obs= tem q ser cada conta pelos 2 metodos adiçao e substituiçao.

1)x-3y=1
2x+5y=13

2)2x+y=10
x+3y=15

3)3x+y=13
2x-y=12

4)2x+7y=17
5x-y=-13

5) 2x+y=4
4x-3y=3

6)x-y=2
3x+2y=6

7)x-y=5
x+y=7

Answer 1

1)x-3y=1
2x+5y=13

x=1+3y

2.(1+3y)+5y=13
2+6y+5y=13
11y=13-2
11y=11
y=11/11
y=1

x=1+3y
x=1+3.1
x=1+3
x=4


2)2x+y=10
x+3y=15

x=15-3y

2.(15-3y)+y=10
30-6y+y=10
-5y=10-30
-5y=-20 (.-1)
5y=20
y=20/5
y=4

x=15-3y
x=15-3.4
x=15-12
x=3


3)3x+y=13
2x-y=12

y=13-3x
2x-(13-3x)=12
2x-13+3x=12
5x=12+13
5x=25
x=25/5
x=5

y=13-3x
y=13-3.5
y=13-15
y=-2


4)2x+7y=17
5x-y=-13

-y=-13-5x (.-1)
y=13+5x

2x+7.(13+5x)=17
2x+91+35x=17
37x=17-91
x=-74/37
x=-2

y=13+5x
y=13+5.(-2)
y=13-10
y=3


5) 2x+y=4
4x-3y=3

y=4-2x

4x-3.(4-2x)=3
4x-12+6x=3
10x=3+12
10x=15
x=1,5

y=4-2x
y=4-2.1,5
y=4-3
y=1


6)x-y=2
3x+2y=6

x=2+y

3.(2+y)+2y=6
6+3y+2y=6
5y=6-6
5y=0
y=0/5
y=0

x=2+y
x=2+0
x=2


7)x-y=5
x+y=7 

x=5+y

5+y+y=7
5+2y=7
2y=7-5
y=2/2
y=1

x-y=5
x-1=5
x=5+1
x=6