Tìm x
a, \(311-x+82=46+\left(x-21\right)\)
b,\(-\left(x-3+85\right)=\left(x+70-71\right)-5\)
c,\(-2\left(x+6\right)+6\left(x-10\right)=8\)
d,\(\left|x\right|=41\)
e, \(\left|-8\right|.\left|x\right|=\left|-56\right|\)
f,\(3.\left|x-2\right|+2x=19\) với \(x\) \(\ge\) 2
Giúp hộ đi ạ, cảm ơn.
a, 311 - x + 82 = 46 + ( x -21 )
311 + 82 -x = 46 + x -21
393 - x = 25 + x
393 - 25 = x + x
368 = 2x
= > x = 184
b,−( x − 3 + 85 ) = ( x + 70 − 71 ) − 5
- x + 3 - 85 = x + 70 - 71 - 5
-x -82 = x - 6
-82 + 6 = x + x
-76 = 2x
x = -38
c,− 2 ( x + 6) + 6 ( x − 10 ) = 8
-2x - 12 + 6x - 60 = 8
-2x+ 6x -12 - 60 = 8
4x -72 = 8
4x = 80
x = 20
d,| x | = 41
=> x = 41 hoặc x = 41
e, | − 8 | . | x | = | −56 |
8 . | x | = 56
=> | x | = 7
=> x=7 hoặc x = -7
f , |x − 2 | + 2 x = 19 với x ≥ 2
Ta có : | x - 2 | + 2x = 19
| x -2 | = 19 - 2x
=> x - 2 = 19-2x hoặc x -2 = - ( 19-2x)
+) x -2 = 19-2x
=> x + 2x = 19 +2
=> x.(2+1 ) = 21
=> x . 3 = 21
=> x =7
+) x-2 = - ( 19 -2x )
=> x -2 = -19 +2x
=> -2 + 19 = 2x -x
=> 17 = x
Vậy x = 17 hoặc x = 7