(2x-5):3+3=24
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a) \(3\dfrac{4}{5}:\dfrac{8}{5}=0,25:x\)
\(\Rightarrow\dfrac{19}{5}.\dfrac{5}{8}=\dfrac{x}{4}\)
\(\Rightarrow\dfrac{x}{4}=2\Rightarrow x=8\)
b) \(2x+\dfrac{3}{24}=3x-\dfrac{1}{32}\)
\(\Rightarrow x=\dfrac{1}{8}+\dfrac{1}{32}=\dfrac{5}{32}\)
c) \(\dfrac{13x-2}{2x+5}=\dfrac{76}{17}\)
\(\Rightarrow221x-34=152x+380\)
\(\Rightarrow69x=414\Rightarrow x=6\)
2: Để \(2x\left(x+1\right)< 0\) thì \(\left\{{}\begin{matrix}x+1\ge0\\x\le0\end{matrix}\right.\Leftrightarrow-1\le x\le0\)
Bạn ơi nếu x ≤ 0 mà x = 0 thì 2x (x+1) = 0
mà 0 = 0 thì sia rồi đúng ko
1) Ta có: \(\left(x+2\right)^2+\left(x-3\right)^2\)
\(=x^2+4x+4+x^2-6x+9\)
\(=2x^2-2x+13\)
2) Ta có: \(\left(4-x\right)^2-\left(x-3\right)^2\)
\(=\left(4-x-x+3\right)\left(4-x+x-3\right)\)
\(=-2x+7\)
3) Ta có: \(\left(x-5\right)\left(x+5\right)-\left(x+5\right)^2\)
\(=x^2-25-x^2-10x-25\)
=-10x-50
4) Ta có: \(\left(x-3\right)^2-\left(x-4\right)\left(x+4\right)\)
\(=x^2-6x+9-x^2+16\)
=-6x+25
5) Ta có: \(\left(y^2-6y+9\right)-\left(y-3\right)^2\)
\(=y^2-6y+9-y^2+6y-9\)
=0
6) Ta có: \(\left(2x+3\right)^2-\left(2x-3\right)\left(2x+3\right)\)
\(=4x^2+12x+9-4x^2+9\)
=12x+18
\(\dfrac{3}{4}\left(2x-5\right)+\dfrac{1}{6}=\dfrac{5}{24}\\ \Rightarrow\dfrac{3}{4}\left(2x-5\right)=\dfrac{1}{24}\\ \Rightarrow2x-5=\dfrac{1}{18}\\ \Rightarrow2x=\dfrac{91}{18}\\ \Rightarrow x=\dfrac{91}{36}\)
1) \(-6x^4+4x^3-2x^2\)
2) \(=x^2+4x-21-x^2-4x+5=-16\)
3) \(=6x^2-4x-x^2-4x-4=5x^2-8x-4\)
4) \(=2x^3-4x^2-8x-3x^2+6x+12=2x^3-7x^2-2x+12\)
17 - 2x = -15
2x = 17 - (-15)
2x = 32
x = 32 : 2
x = 16
--------
54 : (x + 2) = -6
x + 2 = 54 : (-6)
x + 2 = -9
x = -9 - 2
x = -11
--------
12.(3 - x) = 72
3 - x = 72 : 12
3 - x = 6
x = 3 - 6
x = -3
-------
-3(x + 5) + 18 = -27
-3(x + 5) = -27 - 18
-3(x + 5) = -45
x + 5 = -45 : (-3)
x + 5 = 15
x = 15 - 5
x = 10
-------
(x + 5)² = 9
x + 5 = 3 hoặc x + 5 = -3
*) x + 5 = 3
x = 3 - 5
x = -2
*) x + 5 = -3
x = -3 - 5
x = -8
Vậy x = -8; x = -2
--------
(3 - x)³ = 27
(3 - x)³ = 3³
3 - x = 3
x = 3 - 3
x = 0
\(2^x:4=32\\ \Rightarrow2^x=128\\ \Rightarrow2^x=2^7\\ \Rightarrow x=7\)
\(3^{x-2}:3=243\\ \Rightarrow3^{x-2}=729\\ \Rightarrow3^{x-2}=3^6\\ \Rightarrow x-2=6\\ \Rightarrow x=8\)
\(256:4^{x+1}=4^2\\ \Rightarrow4^{x+1}=4^2\\ \Rightarrow x+1=2\\ \Rightarrow x=1\)
\(4^{2x-1}:4=4^4\\ \Rightarrow4^{2x-1}=4^5\\ \Rightarrow2x-1=5\\ \Rightarrow x=3\)
\(5^{x-1}:5=5^3\\ \Rightarrow5^{x-1}=5^4\\ \Rightarrow x-1=4\\ \Rightarrow x=5\)
\(3^{2x+1}:3=3^4\\ \Rightarrow3^{2x+1}=3^5\\ \Rightarrow2x+1=5\\ \Rightarrow x=3\)
36 x 76 - 24 x 39
=2736 - 936
=1800
1992 -(992+95)
= 1992 - 1087
=903
920 - [24 - (5-3)2 ]
=920 -[ 24- 4]
=920 20
=900
5x - 3 = 2002
5x = 2002 +3
5x = 2005
x = 2005 : 5
x = 401
34
\(\left(2x-5\right):3+3=24\\ =>\left(2x-5\right):3=24-3\\ =>\left(2x-5\right):3=21\\ =>2x-5=63\\ =>2x=63+5=68\\ =>x=68:2=34\)