Question

Rozwiąż układy równań

(pisze bez klamerek)

A.

10(y+2) + 3(x-5)=x-5

25(y+2) + 3(x-5) =-10

B.

y/2 + x/4 - 1/5(x+2) =1,1

x-2y +4 = x/2 + 3/4(y-0,5)

C.

x/2=y/3

x+2,5=y

D.

x/5 - y/4 = 0

x/2 - y/16 =5,5

Answer 1

A.

10(y+2) + 3(x-5)=x-5

25(y+2) + 3(x-5) =-10

10y+20+3x-15=x-5

25y+50+3x-15=-10

10y+3x-x=-5-20+15

25y+3x=-10-50+15

10y+2x=-15/*3

25y+3x=-45/*(-2)         *-to jest razy

30y+6x=-45=========>30(-2,25)+6x=-45

-50y-6y=90                  6x=-45+67,5

___________               6x=22,5

-20y=45                       x=3,75

-y=2,25

y=-2,25

 

B.

y/2 + x/4 - 1/5(x+2) =1,1/*20

x-2y +4 = x/2 + 3/4(y-0,5)/*4

10y+5x-4(x+2)=22

4x-8y+16=2x+3(y-0,5)

10y+5x-4x-8=22

4x-8y+16=2x+3y-4,5

x+10y=30

2x-5y=11,5/*2

x+10y=30=========>10y=40,6

4x-10y=23                y=4,06

____________

5x=53

x=10,6

 

C.

x/2=y/3/*6

x+2,5=y/*10

3x=2y/*(-5)

10x+25=10y

-15x=-10y=======>10y=75

10x+25=-10y             y=7,5

____________

-5x=-25

x=5

 

D.

x/5 - y/4 = 0/*20

x/2 - y/16 =5,5

4x-5y=0

x/2-y/16=11/2  /*16

4x-5y=0/*-(2)

8x-y=88

-8x+10y=0

8x-y=88=======>8x=97,8

__________        x=12,2

9y=88

y=9,8