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a, 12 - (2\(x^2\) - 3) = 7
2\(x^2\) - 3 = 12 - 7
2\(x^2\) - 3 = 5
2\(x^2\) = 8
\(x^2\) = 4
\(\left[{}\begin{matrix}x=-2\\x=2\end{matrix}\right.\)
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Giá trị x trong phép tính 10 - 2x = 4 là :
A.5 B.2 C.3 D.7
Kết quả sắp xếp các số -2 ; -3 ; -102 ; -99 theo thứ tự tăng dần là :
A -2 ; -3 ; -99 ; -102
B -102 ; -99 ; -3 ; -2
C -99 ; -102 ; -3 ; -2
D -102 ; -99 ; -2 ; -3
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1: 7-x=8+(-7)
=>7-x=8-7=1
=>x=7-1=6
2: \(x-8=\left(-3\right)-8\)
=>x-8=-11
=>\(x=-11+8=-3\)
3: \(2-x=10-9+23\)
=>\(2-x=33-9=24\)
=>x=2-24=-22
4: \(-2-x=15\)
=>\(x=-2-15=-17\)
5: \(-7+x-8=-3-1+13\)
=>x-14=13-4=9
=>x=9+14=23
6: 100-x+7=-x+3
=>107-x=3-x
=>107=3(vô lý)
7: \(23+x=8-2x\)
=>\(x+2x=8-23\)
=>3x=-15
=>x=-15/3=-5
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A, 89 -(73-x)=20
=> 73 - x = 89 - 20
=> 73 - x = 69
=> x = 73 - 69
=> x = 4
B, 7x - 2x = 617:615 + 44:11
=> ( 7 - 2 ) x = 36 + 4
=> 5x = 40
=> x = 8
C, x - [ 42+(-28)]=-8
=> x - 14 = - 8
=> x = - 8 + 14
=> x = 6
D, 62 - (2x-3):3=23
=> ( 2x - 3 ) : 3 = 62 - 23
=> ( 2x - 3 ) : 3 = 39
=> 2x - 3 = 117
=> 2x = 120
=> x = 60
E, 4(x-3)=72 - 110
=> 4 ( x - 3 ) = 49 - 1
=> 4 ( x - 3 ) = 48
=> x - 3 = 12
=> x = 15
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1)
a) 2x + 5 = 3⁴ : 3²
2x + 5 = 3²
2x + 5 = 9
2x = 9 - 5
2x = 4
x = 4 : 2
x = 2
b) (3x - 24).73 = 2.74
(3x - 24).73 = 148
3x - 24 = 148/73
3x = 148/73 + 24
3x = 1900/73
x = 1900/73 : 3
x = 1900/219
c) [3.(42 - x)] + 15 = 23.3
126 - 3x + 15 = 69
141 - 3x = 69
3x = 141 - 69
3x = 72
x = 72 : 3
x = 24
d) 126 + (132 - x) = 300
132 - x = 300 - 126
132 - x = 174
x = 132 - 174
x = -42
2)
a) 120 - (x + 55) = 60
x + 55 = 120 - 60
x + 155 = 60
x = 60 - 55
x = 5
b) (7x - 11).3 = 25.52 + 200
(7x - 11).3 = 1500
7x - 11 = 1500 : 3
7x - 11 = 500
7x = 500 + 11
7x = 511
x = 511 : 7
x = 73
c) 2x + 2x + 4 = 544
4x = 544 - 4
4x = 540
x = 540 : 4
x = 135
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1/ \(\left\{{}\begin{matrix}\left(x-2\right)^{72}\ge0\\\left(y+1\right)^{70}\ge0\end{matrix}\right.\)
Mà \(\left(x-2\right)^{72}+\left(y+1\right)^{70}=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left(x-2\right)^{72}=0\\\left(y+1\right)^{70}=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x-2=0\\y+1=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=-1\end{matrix}\right.\)
Vậy ...
2/ \(\left\{{}\begin{matrix}\left|x+1\right|\ge0\\\left|y-3\right|\ge0\end{matrix}\right.\)
Mà \(\left|x+1\right|+\left|y-3\right|=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left|x+1\right|=0\\\left|y-3\right|=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=-1\\y=3\end{matrix}\right.\)
Vậy ...
3/ \(\left\{{}\begin{matrix}\left(2x-10\right)^{100}\ge0\\\left(x-y\right)^{102}\ge0\end{matrix}\right.\)
Mà \(\left(2x-10\right)^{100}+\left(x-y\right)^{102}=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left(2x-10\right)^{100}=0\\\left(x-y\right)^{102}=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x-10=0\\x-y=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=5\\y=5\end{matrix}\right.\)
Vậy ....
4/ \(\left\{{}\begin{matrix}\left|2x+8\right|\ge0\\\left|y+x\right|\ge0\end{matrix}\right.\)
Mà \(\left|2x+8\right|+\left|y+x\right|=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left|2x+8\right|=0\\\left|y+x\right|=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2x+8=0\\y+x=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=-8\\y=8\end{matrix}\right.\)
Vậy ..
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Bài 1:
$10+3(x-6)=5^{10}:5^8=5^2=25$
$3(x-6)=25-10=15$
$x-6=15:3=5$
$x=5+6=11$
Bài 2:
a. $100-[150-8(7-4)^2]=100-(150-8.3^2)=100-150+8.3^2$
$=-50+72=72-50=22$
b. $=-999-23+999-10-67=(-999+999)-10-(67+23)$
$=0-10-90=-(10+90)=-100$