Question

1- Resolva os sistemas :

a) 2 x + y = 5
2 x + 8 y = 12

b) X + y = 9
X +3 y = 23

c) 3 X + 7 y = 38
X +7 y =36

d) x - y = 3
X + 3 y = 11

Answer 1

Resposta:

a)

2 x + y = 5 (i)

2 x + 8 y = 12 (ii)

(i)-(ii)   ==>-7y=-7 ==>y=1  

2x+8=12 ==>x=2

b)

x + y = 9 (i)

x +3 y = 23 (ii)

(i)-(ii) ==>-2y=-14 ==>y=7

x+7=9 ==>x=2

c)

3x + 7y = 38 (i)

x +7 y =36 (ii)

(i)-(ii) ==> 2x=2 ==>x=1

1+7y=36 ==>y=5

d)

x - y = 3 (i)  

x + 3 y = 11 (ii)

(i)-(ii) ==> -4y=-8 ==>y=2

x-2=3 ==>x=5