Obtenha o conjunto das soluçoes racionais de cada sistema:
(a) {x+y=4
{x-y=1

(5/2 ,  3/2)

or

(2.5  , 1.5)

(These are the same point; just one is in fraction form and the other in decimal)

Step-by-step explanation:

I could be wrong but I think you want to solve the system

x+y=4

x-y=1

The cool thing about this system it is already set up for elimination (some people call it linear combination).  This means when you add the equations together, a variable will get eliminated allowing you to solve for the other.

x+y=4

x-y=1

Add equations.

2x+0=5

2x    =5

 x     =5/2

 x     =2.5

So plug in your x into either one of the equations and solve for y.

x+y=4

2.5+y=4

y=4-2.5

y=1.5

So the solution is (2.5 , 1.5)  or (5/2, 3/2).

1     3    

step-by-step explanation:

hopefully im right