Question

rozwiązać metodą podstawiania

b

x-y=1

1/3x+1=-1/3y

c

x+2/3y=3

y=7-2x

d

6-x=5

2x+3y=-7

e

x+3=y-1

3x+4=2(y-3)

f

1/3x+2/3y=1

x-2y=7

Answer 1

b)x-y=1

⅓x+1=-⅓y

 

x = 1+y

⅓*(1+y) + 1 = -⅓y

 

⅓ + ⅓y +1 = -⅓y

1⅓ + ⅔y = 0

⅔y = 1⅓

 

y = 2

x = 1+2 = 3

 

 

c)x+⅔y=3

y=7-2x

 

x + ⅔*(7-2x) = 3

x + ¹⁴/₃ - ⁴/₃x = 3

-⅓x = -1⅔

 

x = 5

y = 7-2*5 = 7-10 = -3

 

d) 6-x=5

2x+3y=-7

 

x = 6-5 = 1

 

2*1 + 3y = -7

2 + 3y = -7

3y = -9

 

y = -3

x = 1

 

e)x+3=y-1

3x+4=2(y-3)

 

x = y - 4

3*(y-4) + 4 = 2y - 3

3y - 12 + 4 = 2y - 3

y - 8 = -3

 

y = 5

x = 5-4 = 1

 

f)⅓x+⅔y=1

x-2y=7

 

x = 7 +2y

 

⅓*(7+2y) + ⅔y = 1

⁷/₃ + ⅔y + ⅔y =1

⁴/₃y = -1⅓

 

y = -1

x = 7+ 2 *(-1) = 7-2 = 5