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Tìm x εIN biết
a) 390 - (x-8) = 168:13
b) (x-140) : 7 = 27 - 24
c) x- 6 :2 - ( 48 - 24 ) :2 :6 - 3 = 0
d) x+5.2-(32+16.3:6-15)=0
b) \(\left(x-140\right):7=27-24\)
\(\left(x-140\right):7=3\)
\(x-140=21\)
\(x=161\)
vay \(x=161\)
c) \(x-6:2-\left(48-24\right):2:6-3=0\)
\(x-3-24:2:6-3=0\)
\(x-3-2-3=0\)
\(x-8=0\)
\(x=8\)
vay \(x=8\)
d) \(x+5.2-\left(32+16.3:6-15\right)=0\)
\(x+10-\left(32+8-15\right)=0\)
\(x+10-25=0\)
\(x-15=0\)
\(x=15\)
vay \(x=15\)
a) \(390-\left(x-8\right)=168:13\)
\(390-x+8=\frac{168}{13}\)
\(x+8=390-\frac{168}{13}\)
\(x+8=\frac{5070}{13}-\frac{168}{13}\)
\(x+8=\frac{4902}{13}\)
\(x=\frac{4902}{13}-8\)
\(x=\frac{4798}{13}\)
vay \(x=\frac{4798}{13}\)
(1 + x) + (2 + x) + (3 + x) + ... + (10 + x) = 75
=> (1 + 2 + 3 + ... + 10) + (x + x + x + ... + x) = 75
=> 55 + 10x = 75
=> 10x = 20
=> x = 2
vậy_
x : [(1800 + 600) : 30] = 560 : (315 - 35)
=> x : [2400 : 30] = 560 : 280
=> x : 80 = 2
=> x = 160
vậy_
a, \(x:\left[\left(1800+600\right):30\right]=560:\left(315-35\right)\)
\(\Rightarrow\) \(x:\left[2400:30\right]=560:280\)
\(\Rightarrow\) \(x:80=2\)
\(\Rightarrow\) \(x=160\)
b, \(\left[\left(250-25\right):15\right]:x=\left(450-60\right):130\)
\(\Rightarrow\) \(\left[225:15\right]:x=390:130\)
\(\Rightarrow\) \(15:x=3\)
\(\Rightarrow\) \(x=5\)
x : [(1800 + 600) : 30] = 560 : (315 - 35)
=> x : (2400 : 30) = 560 : 280
=> x : 80 = 2
=> x = 2 . 80
=> x = 160
Vậy x = 160
x : [( 1800 + 600 ) : 30 ] = 560 : ( 315 - 35 )
x : [ 2400 : 30 ] = 560 : 280
x : 80 = 560 : 280
x : 80 = 2
x = 2.80
x = 160
bài 2) a) \(2\left(x+1\right)=0\Leftrightarrow x+1=0\Leftrightarrow x=-1\) vậy \(x=-1\)
b) \(x\left(x-2\right)=0\Leftrightarrow\left\{{}\begin{matrix}x=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=0\\x=2\end{matrix}\right.\) vậy \(x=0;x=2\)
c) \(\left(x-1\right)\left(x+7\right)=0\Leftrightarrow\left\{{}\begin{matrix}x-1=0\\x+7=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1\\x=-7\end{matrix}\right.\) vậy \(x=1;x=-7\)
d) \(\left(x+2\right)\left(x^2-9\right)=0\Leftrightarrow\left\{{}\begin{matrix}x+2=0\\x^2-9=0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=-2\\x^2=9\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=-2\\\left\{{}\begin{matrix}x=3\\x=-3\end{matrix}\right.\end{matrix}\right.\) vậy \(x=-2;x=3;x=-3\)
e) \(x^2\left(x-5\right)+2\left(x-5\right)=0\Leftrightarrow\left(x^2+2\right)\left(x-5\right)=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}x^2+2=0\\x-5=0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x\in\varnothing\\x=5\end{matrix}\right.\) vậy \(x=5\)
bài 1) \(A=48+\left(-48-174\right)+\left|-74\right|=48-48-174+74=-100\)
\(B=\left(-123\right)+77+\left(-257\right)-23-43=-123+77-257-23-43=-369\)
\(C=\left(-57\right)+\left(-159\right)+47+169=-57-159+47+169=0\)
quá hợp lí 
a) \(y-6:2-\left(48-24.2:6-3\right)=0.\)
\(\Rightarrow y-3-\left(48-8-3\right)=0\)
\(\Rightarrow y-3-37=0\)
\(\Rightarrow y=0+37+3=40\)
Vậy y = 40
b) \(\left(7.13+8.13\right):\left(9\frac{2}{3}-y\right)=39\)
\(\Rightarrow195:\left(\frac{29}{3}-y\right)=39\)
\(\Rightarrow\frac{29}{3}-y=195:39=5\)
\(\Rightarrow y=\frac{29}{3}-5=\frac{14}{3}\)
Vậy y=\(\frac{14}{3}\)
a) y - 6 : 2 - ( 48 - 24 x 2 : 6 - 3 ) = 0
y - 6 : 2 - ( 48 - 48 : 6 - 3 ) = 0
y - 6 : 2 - ( 48 - 8 - 3 ) = 0
y - 6 : 2 - 37 = 0
y - 3 = 0 + 37
y - 3 = 37
y = 37 + 3
y = 40
b) ( 7 x 13 + 8 x 13 ) : ( \(9\frac{2}{3}\) - y ) = 39
( 15 x 13 ) : ( \(9\frac{2}{3}\) - y ) = 39
195 : ( \(9\frac{2}{3}\) - y ) = 39
\(9\frac{2}{3}\) - y = 195 : 39
\(9\frac{2}{3}-y=5\)
\(y=9\frac{2}{3}-5\)
\(y=\frac{14}{3}\)
\(\left(19x+2.5^2\right):14=\left(13-8\right)^2-4^2\)
<=> \(\left(19x+50\right):14=25-16\)
<=> \(\left(19x+50\right):14=9\)
<=> \(19x+50=126\)
<=> \(19x=76\)
<=> \(x=4\)
câu B làm j có \(x\)để tìm
\(390-\left(x-7\right)=169:13\)
<=> \(390-x+7=13\)
<=> \(390-x=6\)
<=> \(x=384\)
\(x-6:2-\left(48:24\right):2:6-3=0\)
<=> \(x-3-2:2:6=3\)
<=> \(x-3-\frac{1}{6}=3\)
<=> \(x=\frac{37}{6}\)
\(x+5.2-\left(32+16.3:6-15\right)=0\)
<=> \(x+10-25=0\)
<=> \(x=15\)
a, x : [(1800 + 600) : 30] = 560 : (315 - 35)
<=> x : (2400 : 30) = 560 : 280
<=> x : 80 = 2
<=> x = 160
b, x - 6 : 2 - (48 - 24) : 2 : 6 - 3 = 0
<=> x - 3 - 24 : 2 : 6 - 3 = 0
<=> x - 3 - 2 - 3 = 0
<=> x - 8 = 0
<=> x = 8
c, 390 - (x - 7) = 169 : 13
<=> 390 - (x - 7) = 13
<=> x - 7 = 377
<=> x = 384
d, (x - 140) : 7 = 33 - 23.3
<=> (x - 140) : 7 = 33 - 24
<=> (x - 140) : 7 = 3
<=> x - 140 = 21
<=> x = 161
@Đỗ Thị Huyền Trang
a) x = 160
b) x= 8
c) x = 384
d) x = 539