Răspuns:
Explicație pas cu pas:
a)
-2x + 9y = 7 l *4
8x -5y = 3
-
-8x + 36y = 28
8x - 5 y = 3
.................................
/ 31 y = 31
y= 31/31
y= 1
-
-2x +9 *1= 7
-2x + 9= 7
-2x= 7-9
-2x=-2
x=-2/-2
x= 1
-
S= ( 1,1 )
-
b)
5x + 9y = -6
4x - 3y = -15 l *3
-
5x + 9y = -6
12x - 9y = -45
........................
17x / = - 51
x= -51/17
x=-3
-
5*(-3) +9y =-6
-15+9y= -6
9y= -6+15
9y= 9
y= 9/9
y= 1
-
S= ( -3 ,1)
-
c)
6x - 5y = 17
-3x +7y = -13 l *2
-
6x -5y = 17
-6x +14y = -26
..............................
/ 9y =- 9
y= -9/9
y= - 1
-
6x+5*1= 17
6x+5= 17
6x= 17-5
6x= 12
x= 12:6
x= 2
-
S= ( 2, -1 )
-
-
d)
3x -2y= 13 l*2
8x +4y = 16
-
6x - 4y= 26
8x +4y = 16
........................
14x / = 42
14x=42
x= 42:14
x= 3
-
3x-2y= 13
3*3-2y=13
9-2y= 12
-2y= 13-9
-2y= 4
y= 4/-2
y= -2
-
S= ( 3 , -2)
-
