Răspuns :

Kitty200704id

a)

x+3×a-3×b=20

x+3×(a-b)=20

x+3×6=20

x+18=20

x=20-18

x=2

b)

x×a-x×b+9a-9b=654

x×(a-b)+9(a-b)=654

x×6+9×6=654

x×6+54=654

x×6=654-54

x×6=600

x=600:6

x=100

c)

7×a-7×b+x=55

7×(a-b)+x=55

7×6+x=55

42+x=55

x=55-42

x=13

d)

13+x-(5×a-5×b)=2011

x-[5×(a-b)]=2011-13

x-(5×6)=1998

x-30=1998

x=1998+30

x=2028

HawkEyedid

Răspuns:

a)

x + 3 × a - 3 × b = 20

x + 3 × (a - b) = 20

x + 3 × 6 = 20

x + 18 = 20

x = 20 - 18

x = 2

b)

x × a - x × b + 9a  - 9b = 654   ( posibil ai gresit  exercitiul )

x × (a - b) + 9 × (a - b) = 654

x × 6 + 9 × 6 = 654

6x - 54 = 654

6x = 654 - 54

6x = 600

x = 600 : 6

x = 100  

c)

7 × a - 7 × b + x = 55

7 × (a - b) + x = 55

7 × 6  + x = 55

42 + x = 55

x = 55 - 42

x = 13

d)

13 + x - (5 × a - 5 × b) = 2011

13 + x - 5 × (a - b) = 2011

13 + x - 5 × 6 = 2011

13 + x - 30 = 2011

x - 17 = 2011

x = 2011 + 17

x = 2028