Question

me ajudem pfv
x+y=1
x-y=7

x+22=y
x+y=188

5t+3z=2
t+5z= 1

2x+7y=9
4x-5y=-1

Answer 1

a)

x+y=1   ==>x=1-y

x-y=7   ==>x=7+y

1-y = 7+y

1-7=y+y

2y=-6

y=-3

x=1-(-3)=4

b)

x+22=y   ==>y=x+22

x+y=188 ==>y=188-x

x+22=188-x

x+x=188-22

2x=166

x=83

y=83+22==105

c)

5t+3z=2      

t+5z= 1   ==>t=1-5z

5*(1-5z)+3z=2

5-25z+3z=2

22z=5-2

z=3/22

t=1-5*(3/22)

t=22/22-15/22=7/22

d)

2x+7y=9  ==>vezes 2 ==>4x+14y=18  (i)

4x-5y=-1  (ii)

(i)-(ii)

19y=19

y=1

usando (ii) ==> 4x-5=-1  ==>x= 4/4=1