Question

tìm số tự nhiên x, biết:

a'x+2(3-x)-3(1-x)=9

b'(3x+5)-(x-10)+2x=31

Answer 1

a) x+2(3-x)-3(1-x)=9

<=> x+6-2x-3+3x=9

<=> 2x+3=9

<=> 2x=6

<=> x=3

b) (3x+5)-(x-10)+2x=31

<=> 3x+5-x+10+2x=31

<=> 4x+15=31

<=> 4x=16

<=> x=4

Answer 2

a) x+2(3-x)-3(1-x)=9

        x+6-2x-3+3x=9

               x-2x+3x=9-6+3

                       2x=6

                         x=6:2

                         x=3

Vậy x=3

b) (3x+5)-(x-10)+2x=31

     3x+5-x+10+2x=31

     3x-x+2x=31-5-10

              4x=16 

                x=16:4

                x=4

Vậy x=4

Answer 3

a, x + 2(3 - x) - 3( 1 - x) = 9

<=> x + 6 - 2x - 3 + 3x = 9

<=> x - 2x + 3x = 9 - 6 +3 

<=> 2x = 6

<=> x = 3

Vậy_

b, ( 3x + 5) - ( x - 10) + 2x = 31

<=> 3x + 5 - x + 10 + 2x = 31

<=> 3x - x + 2x = 31 - 5 - 10

<=> 4x =16

<=> x = 4

Vậy_