Odpowiedź:
1.
x -3y=5
4x+5y=3
x= 5 + 3y
4(5 + 3y) + 5y = 3
x = 5 + 3y
20 + 12y + 5y = 3
x= 5 + 3y
20 + 17y = 3
x= 5 + 3y
17y = 3 - 20
x= 5 + 3y
17y = - 17
x = 5 + 3y
y = - 17 : 17
x= 5 + 3y
y = - 1
x = 5 + 3(-1)
y = - 1
x= 5 - 3
y = - 1
x= 2
y = - 1
spr.
4x+5y=3
L= 4x + 5y = 4*2 + 5(-1) = 8 - 5= 3
P= 3
3=3
L=P
2 .
2x+y=20
x-3y= -4
y = 20 - 2x
x - 3(20 - 2x) = - 4
y= 20 - 2x
x - 60 + 6x = -4
y= 20 - 2x
7x - 60 = - 4
y= 20 - 2x
7x = - 4 + 60
y= 20 - 2x
7x = 56
y= 20 - 2x
x= 56 : 7
y= 20 - 2x
x= 8
y = 20 - 2*8
x= 8
y = 20 - 16
x= 8
y = 4
x= 8
spr.
x - 3y = - 4
L= x - 3y = 8 - 3*4 = 8 - 12= - 4
P= - 4
- 4 = - 4
L=P
3.
5x+4y=6
2x+y=3
5x + 4y = 6
y= 3 - 2x
5x + 4(3 - 2x) = 6
y= 3 - 2x
5x + 12 - 8x = 6
y= 3 - 2x
-3x + 12= 6
y= 3 - 2x
-3x = 6 - 12
y = 3 - 2x
- 3x = - 6
y= 3 - 2x
x= - 6 : (-3)
y = 3 - 2x
x = 2
y = 3 - 2x
x= 2
y = 3 - 2 * 2
x= 2
y= 3 - 4
x= 2
y= - 1
spr.
5x + 4y = 6
L= 5x + 4y= 5*2 + 4(-1) = 10 - 4= 6
P= 6
6=6
L=P
4.
4x+y=5
2x-y=-2
y = 5 - 4x
2x - (5 - 4x) = - 2
y= 5 - 4x
2x - 5 + 4x = - 2
y = 5 - 4x
2x + 4x= - 2 + 5
y = 5 - 4x
6x = 3
y= 5 - 4x
x= 3 : 6
y= 5 - 4x
x= 0,5
y= 5 - 4*0,5
x= 0,5
y= 5 - 2
x= 0,5
y= 3
x= 0,5
spr.
4x + y = 5
L= 4x + y= 4*0,5 + 3 = 2 + 3= 5
P= 5
5=5
L=P
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