Odpowiedzi

2009-12-07T21:10:19+01:00
A) 2x-2y=7/2
x-y=3,5
x=3,5+y

4x+3y=21
x=3,5+y

4(3,5 + y) +3y=21
x=3,5+y

14 + 4y + 3y = 21
7y=7/7
y=1
x=4,5

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Najlepsza Odpowiedź!
2009-12-07T21:19:04+01:00
A) 2x-2y=7
4x+3y=21

2x = 7+2y
4x +3y =21

x = (7+2y):2
4(7+2y):2 + 3y =21

x = (7+2y):2
2(7+2y) +3y =21

x = (7+2y):2
14 +4y +3y = 21

x = (7+2y):2
7y = 21-14

x = (7+2y):2
y = 7:7

x = (7+2*1):2
y = 1

x = 4,5
y = 1

b) 0,4x+0,3y=1,4 /*10
0,1x+3y=2,3 /*10

4x +3y = 14
x + 30y = 23

x + 30y = 23
4x +3y = 14

x = 23-30y
4( 23- 30y ) + 3y = 14

x = 23-30y
92 -120y +3y =14

x = 23-30y
-117y =14-92

x = 23-30y
-117y = -78

x = 23-30y
y = 78/117

x = 23-30*(2/3)
y = 2/3

x = 23-20 = 3
y = 2/3

x = 3
y = 2/3


c) 0,5x-2y=8 /*2
2x+5y=6

x -4y = 16
2x +5y = 6

x = 16+4y
2(16+4y) +5y =6

x = 16+4y
32 + 8y +5y = 6

x = 16+4y
13y = 6 -32

x = 16+4y
y = -26 :13

x = 16+4*(-2)
y = -2

x = 16 -8 =8
y = -2

x = 8
y = -2
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