tìm x biết : 1)12+(4-x)=-5 2)-(x+13-142)+18=55 3)-16-(-8-13)=1001-(x-1001)

2 bình luận về “tìm x biết : 1)12+(4-x)=-5 2)-(x+13-142)+18=55 3)-16-(-8-13)=1001-(x-1001)”

1. 1,

   12+(4-x)=-5

   =>12+4-x=-5

   =>16-x=-5

   =>-x=-5-16

   =>-x=-21

   =>x=21

   Vậy x=21

   2,

   -(x+13-142)+18=55

   =>-x-13+142+18=55

   =>-x+147=55

   =>-x=55-147

   =>-x=-92

   =>x=92

   Vậy x=92

   3,

   -16-(-8-13)=1001-(x-1001)

   =>-16+8+13=1001-x+1001

   =>5=-x+2002

   =>-x+2002=5

   =>-x=5-2002

   =>-x=-1997

   =>x=1997

   Vậy x=1997

   Trả lời
2. 1.

   12 + ( 4 – x ) = -5

   ⇒  4 – x  = -5 – 12

   ⇒ 4 – x = – 17

   ⇒ x = 4 – ( – 17 )

   ⇒ x = 21

   Vậy x = 21

   2.

   – ( x + 13 – 142 ) + 18 = 55

   ⇒ – ( x + 13 – 142 ) = 55 – 18

   ⇒  – ( x + 13 – 142 ) = 37

   ⇒ – x – 13 + 142 = 37

   ⇒ – x – 13 = 37 – 142

   ⇒ – x – 13 = – 105

   ⇒ – x = – 105 + 13

   ⇒ – x = – 92

   ⇒ x = 92

   Vậy x = 92

   3.

   – 16 – ( – 8 – 13 ) = 1001 – ( x – 1001 )

   ⇒ – 16 – ( – 21 ) = 1001 – x + 1001

   ⇒ 5 = 2002 – x

   ⇒ x = 1997

   Vậy x = 1997

   Trả lời