720 : [41 - (2x - 5)] = 22 . 5
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280 - ( x - 140 ) : 35 = 270
<=> ( x - 140 ) : 35 = 280 -270
<=> ( x -140 ) : 35 = 10
<=> x -140 = 10 . 35
<=> x -140 = 350
<=> x = 350 + 140
<=> x = 490
1) 280 - ( x - 140 ) : 35 = 270
=> ( x - 140 ) : 35 = 280 - 270 = 10
x - 140 = 350
=> x = 350 + 140
=> x = 390
2) ( 190 - 2x ) : 35 - 32 = 16
190 - 2x = ( 16 + 32 ) . 35 = 1680
x = ( 190 - 1680 ) : 2
x = -745
3) 720 : { 41 - ( 2x - 5 )} -2.5
Sai đề.
4) ( x : 23 + 45 ) . 37 - 22 = 24 .105
x : 23 + 45 = ( 24.105 + 22 ) : 37
x : 23 = 2542/37 - 45 = 877/37
x = 877/37.23 = 20171/37
5) ( 3x - 4 ) ( x - 1 ) = 0
=> 3x - 4 = 0 hoặc x - 1 = 0
3x - 4 = 0 hoặc x - 1 = 0
=> x = 4/3 => x = 1
Vậy x \(\in\) { 4/3;1 }
6) 22x : 4 = 83
=> 22x = 83 . 4 = 2048 = 211
=> 2x = 11
=> x = 11/2
a, 2 3 x + 5 2 x = 2 5 2 + 2 3 - 33
8x+25x = 33
33x = 33
x = 1
b, 260 : x + 4 = 5 2 3 + 5 - 3 3 2 + 2 2
260:(x+4) = 5.13–3.13
x+4 = 260:26
x+4 = 10
x = 6
c, 720 : [ 41 - 2 x - 5 ] = 2 3 . 5
41–(2x–5) = 720:40
2x–5 = 41–18
2x = 28
x = 14
d, 3 2 - 2 x - 12 + 35 = 5 2 + 279 : 3 2
7(x–12)+35 = 56
7(x–12) = 21
x–12 = 3
x = 15
(190-2x):25=270
190-2x =270.25
190-2x =6750
2x =6750-190
2x = 6560
x = 6560/2=3280
720:[41-(2x-5)]=2^3.5
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=14
Còn bài 3 thì mình chịu
c ( 3x2 -6 ) - 43 = 53
( 3x2 -6 ) - 43 = 125
3x2 -6=125+43
3x2 -6=168
3x2=168+6
3x2=174
x2=174:3
x2=58(đề sai)
d) 3x + 2x ( 23 . 5 - 32 . 4 ) + 52 = 44
3x + 2x ( 8 . 5 - 9 . 4 ) + 25 = 256
3x + 2x.4 + 25 = 256
3x + 2x.4=256-25
3x + 2x.4=231
(3+2).x.4=231
5x.4=231
5x=231:4
5x=57,75
x=57,75:5
x=11,55
e) 720 : [ 41 - ( 2x - 5 ) ] = 23 . 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
( ( x . 32 ) - 17 ) . 2 = 42
( ( x . 32 ) - 17 ) = 42 : 2
( ( x . 32 ) - 17 ) = 21
x . 32 = 21 + 17
x . 32 = 38
x = 38 : 32
x = 19/16
720 - [41 - (2x - 5)] = 23.5
720 - [41 - (2x - 5)] = 40
41 - (2x - 5) = 720 - 40
41 - (2x - 5) = 680
2x - 5 = 41 - 680
2x - 5 = - 639
2x = - 639 + 5
2x = - 634
x = - 317
720 - 41 + (2x -5) = 40
2x = 40 +41 +5 - 720
2x = 634
x = 317
\(\text{720 : [41−(2x−5)] = 40720:[41−(2x−5)]=40}\)
\(\text{⇔41−(2x−5)=720:40}\)
\(\text{⇔ 41−2x+5=18}\)
\(\text{⇒ 46 −2x=18}\)
\(\text{⇔2x=28}\)
\(\text{⇔x=14}\)
\(720:\left[41-\left(2x-5\right)\right]=2^2.5\\ =>720:\left(41-2x+5\right)=4.5=20\\ =>46-2x=720:20=36\\ =>2x=46-36=10\\ =>x=5\)
\(720:\left[41-\left(2x-5\right)\right]=2^2\cdot5\)
\(\Rightarrow720:\left[41-\left(2x-5\right)\right]=4\cdot5\)
\(\Rightarrow720:\left[41-\left(2x-5\right)\right]=20\)
\(\Rightarrow41-\left(2x-5\right)=720:20\)
\(\Rightarrow41-\left(2x-5\right)=36\)
\(\Rightarrow2x-5=41-36\)
\(\Rightarrow2x-5=5\)
\(\Rightarrow2x=5+5\)
\(\Rightarrow2x=10\)
\(\Rightarrow x=\dfrac{10}{2}\)
\(\Rightarrow x=5\)