Question

Thu gọn các biểu thức sau:

a)( 71+ x)-( -24- x)+( -35- x).

b) x- 34-[( 15+ x)-( 23- x)].

c)( -15+ lxl)+( -25- lxl).

Answer 1

a) ( 71 + x ) - ( -24 - x ) + ( -35 - x )

= 71 + x + 24 + x - 35 - x

= ( 71 + 24 - 35 ) + ( x + x - x )

= 60 + x

b) x - 34 - [( 15 + x ) - ( 23 - x )]

= x - 34 - ( 15 + x - 23 + x )

= x - 34 - ( 15 - 23 + x2 )

= x - 34 - ( - 8 + 2x )

= x - 34 + 8 - 2x

= x - 2x + 8 - 34

= -x - 26

c) ( -15 + |x| ) + ( -25 - |x| )

= -15 + |x| - 25 + |x|

= -15 - 25 + x + x

= -40 + x2

Answer 2

a)(71+x)-(-24-x)+(-35-x)

=>71+x+24+x-35-x

=>60+x

b)x-34-[(15+x)-(23-x)]

=>x-34-(15+x-23+x)

=>x-34-15-x+23-x

=-x-26

Answer 3

71 + ( 26 - 3 . x ) ; 5 = 75 

        ( 26 - 3x ) : 5 = 75 - 71 

         ( 26 - 3x ) : 5 = 4 

          26 - 3x = 4.5 

          26 - 3x = 20

               3x = 26 - 20

               3x = 6

                x = 6 : 3 

                x = 2