Thursday, January 12, 2012

Verify if the solution of the system of equations (x-5)*y=4 and (x-y)o6=12 has integer solutions given that x*y=x+y-5 and xoy=xy-5(x+y)+30

We'll re-write the equations of the system, using the
given laws of composition.


(x-5)*y=4,
where


x*y=x+y-5


We'll
substitute x by (x-5).


(x-5)*y = x - 5 + y -
5


We'll combine like terms:


x
+ y - 10 = 4


x + y = 10+4


x +
y = 14 (1)


Now, we'll re-write the second equation of the
system using the second law of
composition.


(x-y)o6=12


xoy=xy-5(x+y)+30


We'll
substitute x by (x-y) and y by 6:


(x-y)o6 = 6(x-y) -
5(x-y+6) + 30


We'll remove the
brackets:


6x - 6y - 5x + 5y - 30 + 30 =
12


We'll eliminate and combine like
terms:


x - y = 12 (2)


We'll
solve the system formed from (1) and (2). We'll add (1) +
(2):


x + y + x - y = 14 +
12


We'll eliminate and combine like
terms:


2x = 26


x
= 13


We'll substitute x in
(1):


x + y = 14


13 + y =
14


y = 14 - 13


y =
1


Since both values are integers, we'll
validate them, therefore the solution of the system is: {13 ,
1}.

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