20. Rozwąż układ równań ;
b) { 2x+5=7y
{ 2(x+2)-7y=-1

c) { 3(x+y)-2(y+3)=y+3(x-2)
{ x-2y=5

d) { 2x+5y=2
{ 3(x+y)+2y=3

e) { x+2y=5
{ 2x+4(y-2)=0

f) { 3x-10y=5
{ 10x-3y=47

g) { 5x-y-2=0
{ 15{x-0,5)-2y=y

h) { 2x-y=1
{ 3(2x-y)-4 (1-x)= 3y-1

1

Odpowiedzi

Najlepsza Odpowiedź!
2010-02-02T11:50:29+01:00
B) { 2x+5=7y
{ 2(x+2)-7y=-1
2x+5=7y
2x+4-7y=-1
2x+5=7y
2x=-1-4+7y
x=-5/2+7/2y

2(-5/2+7/2y)+5=7y
-5+7y+5=7y
-5+5=7y-7y
0=y
y=0

x=-5/2+7/2x0
x=-5/2+0
x=-2i1/2
y=0



c) { 3(x+y)-2(y+3)=y+3(x-2)
{ x-2y=5
3x+3y-2y-6=y+3x-6
x=5+2y
3y-2y-y=3x-3x-6+6
0y=0
y=0
x-2y=5
x-2x0=5
x-0=5
x=5
y=0

d) { 2x+5y=2
{ 3(x+y)+2y=3

2x=2-5y
3x+3y+2y=3
x=1-5/2y
5y=3-3x
5y=3-3(1-5/2y)
5y=3-3+15/2y
5y-7i1/2y=0
-2i1/2y=0
y=0
x=1-5/2x0
x=1-0
x=1
y=0


e) { x+2y=5
{ 2x+4(y-2)=0
x=5-2y
2x+4y-8=0
2(5-2y)+4y-8=0
10-4y+4y-8=0
0y=2
y=0
x=5-2x0
x=5-0
x=5
y=0

f) { 3x-10y=5
{ 10x-3y=47
3x=5+10y
x=5/3+10/3y
10(5/3+10/3y)-3y=47
50/3+100/3y-3y=47
33i1/3y-3y=47-16i2/3
30i1/3y=30i1/3
y=1
x=5/3+10/3x1
x=5/3+10/3
x=15/3
x=5
y=1


g) { 5x-y-2=0
{ 15{x-0,5)-2y=y

-y=2-5x
y=5x-2
15x-7,5-2y=y
15x-7,5-2(5x-2)=5x-2
15x-7,5-10x+4=5x-2
15x-10x-5x=-2-4+7,5
0x=1,5
x=0
y=5x0-2
y=0-2
y=-2
x=0

h) { 2x-y=1
{ 3(2x-y)-4 (1-x)= 3y-1

-y=1-2x
y=2x-1
6x-3y-4+4x=3y-1
10x=-1+4+3y+3y
10x=3+6y
10x=3+6(2x-1)
10x=3+12x-6
10x-12x=-3
-2x=-3
x=3/2
y=2(3/2)-1
y=3-1
y=2
x=1i1/2