Question

1 - Resolva os sistemas abaixo.

a)2x +y=7
×-y=8

b)
X-y=5
3×(×+y) - 27


c)
2×-y = 7
×+5y=-2


d)
3a=16+b
2(a+1)-3(b+2)=a​

Answer 1

Resposta:

a)

2x +y=7   (i)

×-y=8   (ii)

(i)+(ii)

3x=15  =>x=5

usando (ii) ==>5-y=8 ==>y=-3

b)

x-y=5   (i)

3*(×+y) - 27  ==>x+y=-9  (ii)

(i)+(ii)

2x=-4  ==>x=-2

Usando (ii) ==>-2+y=-9 ==>y=-7

c)

2×-y = 7   (i)

×+5y=-2  ==> 2x+10y=-4  (ii)

(i)-(ii)

-11y=11==>y=-1

Usando (i) 2x+1=7  ==> x=3

d)

3a=16+b ==>3a-b=16 ==>9a-3b=48 (i)

2(a+1)-3(b+2)=a​  ==>2a+2-3b-6=a ==>a-3b=4    (ii)

(i)-(ii)

8a=44 ==>a=11/2

usando (ii)  ==11/2-3b=4  ==>3b=11/2-8/2  ==>b=1/2