Odpowiedzi

2009-12-07T19:24:09+01:00
A) 5x-y=7
2(x+1)=2y
5x-y=7 (*-2)
2x-2y=-2
-10x+2y=-14
2x-2y=-2
-8x=-16(/-8)
x=2
5x-y=7
10-y=7
-y=7-10
-y=-3 (*-1)
y=3
b) 4(x-2)-y=1
2x-4y=8
4x-8-y=1
2x-4y=8
4x-y=9
2x-4y=8(*-2)
4x-y=9
-4x+8y=-16
7y=-7
y=-1
4x-y=9
4x=9-1
4x=8(/4)
x=2
c) a/3 +b/5=7 (*3)
a/4-b/5=0(*4)
a+3b/5=21 (*5)
a-4b/5=0 (*-5)
5a+3b=105
-5a+4B=0
7B=105
B=15
5a+3b=105
5a+45=105
5a=105-45
5a=60 (/5)
a=12