Odpowiedzi

2009-12-18T20:11:05+01:00
1.
7x+3y=-1 /*2
2x+5y=14 /*(-7)

14x+6y=-2
-14x-35y=-98
-----------------
-29y=-100 /:(-29)
y=100/29

2x=14-5y
2x=14-5* 100/29
2x=14- 500/29
2x=406/29 - 500/29
2x=-94/29 /:2
x=-47/29

2.
4(x-2)-y=1
2x-4y=8

4x-8-y=1
2x-4y=8 /*(-2)

4x-y=1+8
-4x+8y=-16
-----------------
7y=-16+9
7y=-7 /:7
y=-1

2x=8+4y
2x=8+4*(-1)
2x=8-4
2x=4 /:2
x=2

3.
5x-y=7
2(x+1)=2y

5x-y=7
2x+2=2y

5x-y=7
2x-2y=-2 /:(-2)

5x-y=7
-x+y=1
--------------
4x=8 /:4
x=2

y=1+x
y=1+2
y=3

4.
4(x-2)-(y-2)=1
10x+2y=18

4x-8-y+2=1
10x+2y=18 /:2

4x-y=1+6
5x+y=9
----------------
9x=16 /:9
x=16/9

y=9-5x
y=9- 5*16/9
y=81/9 - 80/9
y=1/9

5.
6x-9y=6 /*(-4)
8x+5y=7/3 /*3

-24x+36y=-24
24x+15y=7
----------------
51y=-17 /:51
y=-1/3

6x=6+9y
6x=6+ 9*(-1/3)
6x=6-3
6x=3 /:6
x=3/6
x=1/2