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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
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
\(720:\left[41-\left(2x-5\right)\right]=2^2.5\\ =>720:\left(41-2x+5\right)=4.5=20\\ =>46-2x=720:20=36\\ =>2x=46-36=10\\ =>x=5\)
\(720:\left[41-\left(2x-5\right)\right]=2^2\cdot5\)
\(\Rightarrow720:\left[41-\left(2x-5\right)\right]=4\cdot5\)
\(\Rightarrow720:\left[41-\left(2x-5\right)\right]=20\)
\(\Rightarrow41-\left(2x-5\right)=720:20\)
\(\Rightarrow41-\left(2x-5\right)=36\)
\(\Rightarrow2x-5=41-36\)
\(\Rightarrow2x-5=5\)
\(\Rightarrow2x=5+5\)
\(\Rightarrow2x=10\)
\(\Rightarrow x=\dfrac{10}{2}\)
\(\Rightarrow x=5\)
a){720:[41-(7.2\(^2\)- X)] }:(2\(^3\).5)=1
{720:[41-(7.4-X)] }:(8.5)=1
{720:[41-(28-X)] }:40=1
41-(28-X):40=1.720
41-(28-X):40=720
(28-X):40=720+41
(28-X):40=716
28-X =716.40
28-X=28640
X=28-28640
X=(-28612)
b)420+65.4=(x+175):5+30
420+260=(x+175):5+30
280=(x+175):5+30
(x+175):5=280-30
(x+175):5=250
x+175=250.5
x+175=1250
x=1250-175
x=1075
c)(32.15):2=(x+70):14-40
480:2=(x+70):14-40
240=(x+70):14-40
(x+70):14=240+40
(x+70):14=280
x+70=280.14
x+70=3920
x=3920-70
x=3850
a, 3 ( x+2 ) + 2 ( x-3 ) =10
3x + 6 + 2x - 6 = 10
5x = 10
x = 10 : 5
x = 2
b, 720 : ( 41 - ( 2x-5 )) = 40
720 : ( 41-2x + 5) = 40
720 : ( 46 - 2x ) = 40
46 - 2x = 720 : 40
46 - 2x = 18
2x = 46 - 18
2x = 28
x= 28 : 2
x = 14
Trả lời
720:[41-(2x-5)]=120
41-(2x-5)=720:120
41-(2x-5)=6
2x-5 =41-6
2x-5 =35
2x =35+5
2x =40
=>x =40:2
=>x =20
Học tốt !
(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
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