Question

El conjunto solucion del sistema
3x+2y=4
2x-3y=7
es:
a) (2,1)
b) (1,2)
c) (2,-1)
d) (-2,1)

Answer 1

{3x+2y=4;

2x-3y=7 } ;

2x-3y=7; ------>>>> 2x= 7+ 3y;
X= 7/2+ 3/2y;

3x+ 2y=4; ---->>> 3• (7/2+ 3/2y)+ 2y=4;
21/2+9/2y+2y=4;
9/2y+ (2•2)/(1•2)y= (4•2)/(1•2) - 21/2;
9/2y+ 4/2y= 8/2- 21/2;
13/2y= -13/2;
Y= (-13/2) : 13/2;
Y= (-13/2)• 2/13
Y= (-1/1)• 1/1;

Y=(-1).


X= 7/2+ 3/2y; ------>>>> X = 7/2+ 3/2• (-1);
X= 7/2+ (- 3/2);
X= 7/2- 3/2;

X= 4/2= 2;
_________________
3x+2y=4;

 3• 2+ 2• (-1)=4;
6+(-2)= 4;
6-2=4;
4=4;


2x-3y=7;
2• 2-3•(-1)=7;
4-(-3)= 7;
4+3=7;
7=7;


es:


c) (2,-1)