Question

Tolong bantu jawab 3 nomor itu beserta caranya.. besok dikumpul

Answer 1

jawabannya:

20. x-y/3=5

3x-y=15 (pers 1)

x+3/2y=-6

2x+3y=-12   (pers 2)

subtitusi pers 1

3x-y=15

-y=15-3x

y=-15+3x

2x+3y=-12

2x+3(-15+3x)=-12

2x-45+9x=-12

11x=-12+45

11x=33

x=3

y=-15+3x

=-15+3(3)

=-15+9

=-6

x=3 dan y=-6   (3,-6)

jawabannya C

21 x/4 + y/3 = 1

3x+4y=12 (pers 1)

x/12 - 2/3y =5

x - 8y=60 (pers 2)

subsitusi pers 2

x - 8y =60

x=60+8y

3x+4y=12

3(60+8y)+4y=12

180+24y+4y=12

28y=12-180

28y=-168

y=-6

x=60+8y

=60+8(-6)

=60-48

=12

x= 12 dan y =-6

22 0,02x-0,05y=2,1

2x-5y=210 (pers 1)

0,1 x+0,3y=5

x+3y=50 (pers 2)

subtitusi pers 2

x+3y=50

x=50-3y

2x-5y=210

2(50-3y)-5y=210

100-6y-5y=210

-11y=210-100

-11y=110

y=-10

x=50-3y

=50-3(-10)

=50+30

=80

x=80 dan y=-10