1 Tìm x
a.(x-1)3=125
b2x-2x-2x=96
c.720:[41-(2x-5)]=23.5
Bài 2 (1,5 điểm): Tìm x
a) 9(x + 28) = 0 b) 720 : [41 – (2x – 5)] = 23.5
9. (x + 28) = 0
x + 28 = 0: 9
x + 28 = 0
x = 0 – 28
x = -28
Vậy x = -28.
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
Vậy x=14
b) 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
Vậy x=14
chắc vại ;-;
Tìm số tự nhiên x biết rằng
720:[41-(2x-5)]=23.5
(x+1)+(x+2)+(x+3)+…+(x+100)=5750
a: =>41-(2x-5)=720:40=18
=>2x-5=23
=>2x=28
=>x=14
b: =>100x+5050=5750
=>100x=700
=>x=7
a: =>41-(2x-5)=720:40=18
=>2x-5=23
=>2x=28
=>x=14
b: =>100x+5050=5750
=>100x=700
=>x=7
Tìm x biết:
a, 2 3 x + 5 2 x = 2 5 2 + 2 3 - 33
b, 260 : x + 4 = 5 2 3 + 5 - 3 3 2 + 2 2
c, 720 : [ 41 - 2 x - 5 ] = 2 3 . 5
d, 3 2 - 2 x - 12 + 35 = 5 2 + 279 : 3 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
Tìm số tự nhiên x biết:
a, 128 – 3(x+4) = 23
b, 12 x - 4 3 . 8 3 = 4 . 8 4
c, [(4x+28).3+55]:5 = 35
d, 720:[41 – (2x – 5)] = 2 3 . 5
a, 128 – 3(x+4) = 23
b, 12 x - 4 3 . 8 3 = 4 . 8 4
c, [(4x+28).3+55]:5 = 35
d, 720:[41 – (2x – 5)] = 2 3 . 5
720:[41-(2x-5)]=23.5
720 : [ 41 - ( 2x - 5 ) ] =23 . 5
720 : [ 41 - ( 2x - 5 ) ] = 115
41 - ( 2x -5 ) =720 : 115
41 - ( 2x - 5 ) = 144/23
2x - 5 = 41 - 144/23
2x - 5 =799/23
2x = 799/23 + 5
2x = 914/23
x = 914/23 : 2
x = 914/23 . 1/2
x = 457/23
Vậy x = 457/23
\(720:\left[41-\left(2x-5\right)\right]=23.5\)
\(720:\left[41-\left(2x-5\right)\right]=115\)
\(41-\left(2x-5\right)=720:115\)
\(41-\left(2x-5\right)=\frac{144}{23}\)
\(2x-5=41-\frac{144}{23}\)
\(2x-5=\frac{799}{23}\)
\(2x=\frac{799}{23}+5\)
\(2x=\frac{914}{23}\)
\(x=\frac{914}{23}:2\)
\(x=\frac{457}{23}\)
bài 1: tìm x thuộc Z
m) (1900-2x):35 - 32 = 16
n) 720:[41 - (2x - 5)] = 2 mũ 3 . 5
o) (x-5).(x mũ 2 - 4) = 0
m , Ta có : \(\left(1900-2.x\right):3-32=16\)
\(\Leftrightarrow\frac{1900-2.x}{35}-32=16\)( Nhân hai vế với 35 )
\(\Leftrightarrow1900-2.x-1120=560\)
\(\Leftrightarrow780-2.x=560\)
\(\Leftrightarrow-2.x=560-780\)
\(\Leftrightarrow\) \(-2.x=-220\)
\(\Rightarrow x=110\)
Vậy x = 110
n, Ta có : \(720:\left[41-\left(2.x-5\right)\right]=2^3.5\)
\(\Leftrightarrow720:\left(41-2.x+5\right)=8.5\)
\(\Leftrightarrow720:\left(46-2.x\right)=40\)
\(\Leftrightarrow\frac{720}{46-2.x}=40\)
\(\Leftrightarrow\frac{720}{2.\left(23-x\right)}=40\)
\(\Leftrightarrow\frac{360}{23-x}\)
\(\Leftrightarrow360=40.\left(23-x\right)\)
\(\Leftrightarrow9=23-x\)
\(\Leftrightarrow x=14\)
Vậy x = 14
o, Ta có : \(\left(x-5\right).\left(x^2-4\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-5=0\\x^2-4=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=5\\x=\pm2\end{cases}}\)
Vậy \(x=5;-2;2\)
Tìm x
(x+1) + (x+2) + ...+(x+100)=5750
720 : [41- (2x-5)] =23 .5
a ) (x+1)+...+(x+100)
= (x+x+..+x)+(1+..+100)
=100x + (100+1).100:2
=100x + 5050
=5750
<=> 100x = 5750 - 5050
<=> 100x = 700
=> x = 700 : 100 = 7
b) 720 : [ 41-(2x-5)]= 40
41-(2x-5) = 720 : 40
41-(2x-5) = 18
2x-5 = 41-18= 23
2x = 23+5 = 28
=> x = 28:2 = 14
Chúc Bạn Học Tốt
Nếu sai thì thông cảm ạ
tìm x biết 720 : [ 41- (2x -5) ] = 2^3 .5
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
2.x=23+5
2.x=28
x=28:2
x=14
tìm X
720:[41-(2x-5)]=8.5
1+2+3+4.........+(x-1)+x=78
5x(4x+2)+ 3x=53
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
Vậy x = 14
1 + 2 + 3 + 4 + ... + (x - 1) + x = 78
có x số hạng
=> (x + 1) . x : 2 = 78
=> (x + 1) . x = 78 . 2
=> (x + 1) . x = 156
=> (x + 1) . x = 13 . 12
=> x = 12
Vậy x = 12
1.tìm x
a,128-3.(x=4)=23 b,[(4x =28).3=55]:5=35
c,(12x-4^3).8^3=4.8^4 d,720 :[41-(2x-5)]=263.5
\(a,128-3.\left(x+4\right)=23\\ \Rightarrow3.\left(x+4\right)=105\\ \Rightarrow x+4=35\\ \Rightarrow x=31\\ b,\left[\left(4x+28\right).3+55\right]:5=35\\ \Rightarrow\left(4x+28\right).3+55=175\\ \Rightarrow4x+28.3=120\\ \Rightarrow4x+28=60\\ \Rightarrow4x=32\\ \Rightarrow x=8.\)
c) \(\left(12x-4^3\right).8^3=4.8^4\)
\(12x-64=4.8^4:8^3\)
\(12x-64=32\)
\(12x=32+64\)
\(12x=96\)
\(x=\dfrac{96}{12}\)
\(x=8\)
d) \(720:\left[41-\left(2x-5\right)\right]:5=35\)
\(720:\left(41-2x+5\right):5=35\)
\(720:\left(46-2x\right)=35.5\)
\(720:\left(46-2x\right)=175\)
\(46-2x=720:175\)
\(46-2x=\dfrac{144}{35}\)
\(2x=46-\dfrac{144}{35}\)
\(2x=\dfrac{1466}{35}\)
\(x=\dfrac{1466}{35}:2\)
\(x=\dfrac{733}{35}\)