Bài 6 . Tìm x biết: 1) 58 + 7x = 100 AI LM ĐC MÌNH CHO 20 XU
2) 101 +(36 – 4x) =105
3) 3x – 7 = 28
4) ( x – 12):12=12
5) x – 56 : 4= 16
6) (3.x-2 4 ).73=2.74
7) 71 – (33 + x) = 26
8) = 7 10) 4(x + 41) = 400
9) 45 – (x + 9):2 = 6
11) 2. (x + 7) – 25 = 13
13) 2(x- 51) = 2.23 + 20
15) 450 : (x – 19) = 50
17) 10 - (x – 3): 2 = 72 – 1 10
19) 2x + 2 – 2 x = 48
8) 140 : (x – 12) 5(x – 9) = 350
14) 2x – 49 = 5.32
16) 200 – (2x + 6) = 43
18) 135 – 5.(x + 4) = 35
20) (3x – 5)3 – 1 = 26
\(1,\Leftrightarrow7x=42\Leftrightarrow x=6\\ 2,\Leftrightarrow36-4x=4\Leftrightarrow4x=32\Leftrightarrow x=8\\ 3,\Leftrightarrow3x=35\Leftrightarrow x=\dfrac{35}{3}\\ 4,\Leftrightarrow x-12=144\Leftrightarrow x=156\\ 5,\Leftrightarrow x-14=16\Leftrightarrow x=30\\ 6,\Leftrightarrow3x-24=\dfrac{148}{73}\Leftrightarrow3x=\dfrac{1900}{73}\Leftrightarrow x=\dfrac{1900}{219}\\ 7,\Leftrightarrow33+x=45\Leftrightarrow x=12\\ 8,Sai.đề\\ 9,\Leftrightarrow\left(x+9\right):2=39\Leftrightarrow x+9=78\Leftrightarrow x=69\\ 11,\Leftrightarrow2\left(x+7\right)=38\Leftrightarrow x+7=19\Leftrightarrow x=12\\ 13,\Leftrightarrow2\left(x-51\right)=66\Leftrightarrow x-51=33\Leftrightarrow x=84\)
\(15,\Leftrightarrow x-19=9\Leftrightarrow x=28\\ 17,\Leftrightarrow\left(x-3\right):2=48\Leftrightarrow x-3=96\Leftrightarrow x=99\\ 19,\Leftrightarrow0x=46\Leftrightarrow x\in\varnothing\\ 8,Sai.đề\\ 14,\Leftrightarrow2x=209\Leftrightarrow x=\dfrac{209}{2}\\ 16,\Leftrightarrow2x+6=157\Leftrightarrow2x=151\Leftrightarrow x=\dfrac{151}{2}\\ 18,\Leftrightarrow5\left(x+4\right)=100\Leftrightarrow x+4=20\Leftrightarrow x=16\\ 20,\Leftrightarrow\left(3x-5\right)^3=27=3^3\Leftrightarrow3x-5=3\Leftrightarrow x=\dfrac{8}{3}\)
