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Bài 1: 25 + 3(x - 8) = 106
3(x - 8) = 106 - 25
3(x - 8) = 81
(x - 8) = 81 : 3
(x - 8) = 27
x = 27 + 8
x = 25
Bài 2: 720 : [41 - (2x - 5)] = 23 . 5
720 : [41 - (2x - 5)] = 8 . 5
720 : [41 - (2x - 5)] = 40
[41 - (2x - 5)] = 720 : 40
[41 - (2x - 5)] = 18
(2x - 5) = 41 - 18
(2x - 5) = 23
2x = 23 + 5
2x = 28
x = 28 : 2
x = 14
\(720:\left[41-\left(2x-5\right)\right]=2^3.5\)
\(720:\left[41-\left(2x-5\right)\right]=8.5\)
\(720:\left[41-\left(2x-5\right)\right]=40\)
\(41-\left(2x-5\right)=720:40\)
\(41- \left(2x-5\right)=18\)
\(2x-5=41-18\)
\(2x-5=23\)
\(2x=23+5\)
\(2x=28\)
\(x=28:2\)
\(\Rightarrow x=14\)
720:(41-(2x-5)) =2\(^3\)x5
720:(41-(2x-5)) =40
41-(2x-5) =720:40=18
2x-5 =41-18=23
2x =23+5=28
=> x =28:2=14
x=14
k nha.đúng 100% đó
720 : [41-(2x-5)] = 2^3 . 5
720 : [41-(2x-5) ] =40
=> 41-(2x-5) =18
=> 2x-5 =23
=> 2x =28
=> x=14
720: ( 41-(2x-5) ) = 23 . 5
<=> 720 : ( 41 - ( 2x-5 ) ) = 8.5
<=> 720 : ( 41 - (2x -5 ) ) = 40
<=> ( 41 - ( 2x - 5) ) = 720 : 40 = 18
<=> 2x - 5 = 41 -18 = 23
<=> 2x = 23+5 =28
=> x = 28 : 2 =14
\(720:\left[41-\left(2x-5\right)\right]=2^3.5\)
\(\Leftrightarrow720:\left[41-\left(2x-5\right)\right]=40\)
\(\Leftrightarrow41-\left(2x-5\right)=720:40\)
\(\Leftrightarrow41-\left(2x-5\right)=18\)
\(\Leftrightarrow2x-5=41-18\)
\(\Leftrightarrow2x-5=23\)
\(\Leftrightarrow2x=28\)
\(\Leftrightarrow x=14\)
Ta có :\(720:\left[41-\left(2X-5\right)\right]=2^3\cdot5\)
\(\Leftrightarrow41-\left(2X-5\right)=18\)
\(\Leftrightarrow2X-5=23\)
\(\Leftrightarrow2X=28\)
\(\Leftrightarrow X=14\)(TMĐK)
Vậy X= 14 là giá trụ cần tìm.
1/a) 12 - x= 1-(-5)
12 - x = 6
x= 12-6
x=6
b)| x+4|= 12
x+4 = \(\pm\)12
*x+4=12
x=8
*x+4= -12
x=-16
2/Tìm n
\(n-5⋮n+2\)
=> \(n+2-7⋮n+2\)
mà \(n+2⋮n+2\)
=> 7\(⋮\)n+2
=> n+2 \(\varepsilon\)Ư(7)= {1;-1;7;-7}
| n+2 | 1 | -1 | 7 | -7 |
| n | -1 | -3 | 5 | -9 |
3/a)4.(-5)2 + 2.(-12)
= 2.2.(-5)2 + 2.(-12)
=2[2.25.(-12)]
=2.(-600)
=-1200
a, \(3^2\left(x+14\right)-5^2=5.4\)
\(\Rightarrow9\left(x+14\right)-25=20\)
\(\Rightarrow9x+126=20+25\)
\(\Rightarrow9x+126=45\)
\(\Rightarrow9x=45-126\)
\(\Rightarrow9x=-81\Rightarrow x=-9\)
Vậy x = 9
a,\(3^2\left(x+14\right)-5^2=5.4\)
\(\Rightarrow9\left(x-14\right)-25=20\)
\(\Rightarrow9\left(x-14\right)=20+25=45\)
\(\Rightarrow x-14=45:9=5\)
\(\Rightarrow x=5+14\)
\(\Rightarrow x=19\)
Vậy x = 19
b,\(720:\left[41-\left(2x-5\right)\right]=2^3.5\)
\(720:\left[41-2x+5\right]=40\)
\(\Rightarrow41+5-2x=720:40\)
\(\Rightarrow46-2x=18\)
\(\Rightarrow2x=46-18=28\)
\(\Rightarrow x=28:2\)
\(\Rightarrow x=14\)
Vậy x = 14
~Study well~