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e)| \(\dfrac{5}{2}\)x-\(\dfrac{1}{2}\) |-(-22).\(\dfrac{1}{3}\)(0,75-\(\dfrac{1}{7}\))=\(\dfrac{-5}{13}\):2\(\dfrac{9}{13}\)-0,5.(\(\dfrac{-2}{3}\))
f)| 5x+21 | = | 2x -63 |
g) -45 - |-3x-96 | - 54=-207
Làm ơn giúp mình với ạ!Mình đang cần gấp lắm trong ngày hôm nay ạ!!!Mình xin cảm ơn các bạn nhiều nhiều lắm luôn đó!!!Thank you very much!!!(^-^)
a, (\(\dfrac{2}{9}\)(6x - \(\dfrac{3}{4}\)) - 3(\(\dfrac{1}{4}x-\dfrac{1}{5}\)) = \(\dfrac{-8}{15}\)
<=> (\(\dfrac{4}{3}x-\dfrac{1}{6}\)) - (\(\dfrac{3}{4}x-\dfrac{3}{5}\)) = \(\dfrac{-8}{15}\)
<=> \(\dfrac{4}{3}x-\dfrac{1}{6}-\dfrac{3}{4}x+\dfrac{3}{5}=\dfrac{-8}{15}\)
<=> \(\dfrac{7}{12}x+\dfrac{13}{30}=\dfrac{-8}{15}\)
<=> \(\dfrac{7}{12}x=\dfrac{-8}{15}-\dfrac{13}{30}\)
<=> \(\dfrac{7}{12}x=-\dfrac{29}{30}\)
<=> x = \(-\dfrac{58}{35}\)
@Nguyễn Gia Hân
Bài 1:
a: =>13x+8=9x+20
=>4x=12
hay x=3
b: \(\Leftrightarrow5x-7=-8-11-3x\)
=>5x-7=-3x-19
=>8x=-12
hay x=-3/2
c: \(\Leftrightarrow\left[{}\begin{matrix}12x-7=5\\12x-7=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=\dfrac{1}{6}\end{matrix}\right.\)
e: =>3x+1=-5
=>3x=-6
hay x=-2
a, \(\frac{x-4}{12}=\frac{x-6}{11}\)
\(\Rightarrow11\left(x-4\right)=12\left(x-6\right)\)
\(\Rightarrow11x-44=12x-72\)
\(\Rightarrow11x-12x=-72+44\)
\(\Rightarrow-x=-28\)
=> x = 28
b, \(\frac{3x+2}{-7}=\frac{x-4}{-2}\)
\(\Rightarrow-2\left(3x+2\right)=-7\left(x-4\right)\)
\(\Rightarrow-6x+\left(-4\right)=-7x-\left(-28\right)\)
\(\Rightarrow-6x+\left(-4\right)=-7x+28\)
\(\Rightarrow-6x+7x=28-\left(-4\right)\)
\(\Rightarrow x=32\)
c, \(\frac{1-4x}{5}=\frac{2x-1}{-3}\)
\(\Rightarrow-3\left(1-4x\right)=5\left(2x-1\right)\)
\(\Rightarrow-3-\left(-12x\right)=10x-5\)
\(\Rightarrow-3+12x=10x-5\)
\(\Rightarrow-3+5=10x-12x\)
\(\Rightarrow2=-2x\)
=> x = 2 : (-2)
=> x = -1
\(8-12x+6x^2-x^3\)
\(=\left(2-x\right)^3\)
\(125x^3-75x^2+15x-1\)
\(=\left(5x-1\right)^3\)
\(x^2-xz-9y^2+3yz\)
\(=\left(x-3y\right)\left(x+3y\right)-z\left(x-3y\right)\)
\(=\left(x-3y\right)\left(x+3y-z\right)\)
\(x^3-x^2-5x+125\)
\(=\left(x+5\right)\left(x^2-5x+25\right)-x\left(x+5\right)\)
\(=\left(x+5\right)\left(x^2-5x+25-x\right)\)
\(=\left(x+5\right)\left(x^2-6x+25\right)\)
\(x^3+2x^2-6x-27\)
\(=x^3+5x^2+9x-3x^2-15x-27\)
\(=x\left(x^2+5x+9\right)-3\left(x^2+5x+9\right)\)
\(=\left(x-3\right)\left(x^2+5x+9\right)\)
\(12x^3+4x^2-27x-9\)
\(=4x^2\left(3x+1\right)-9\left(3x+1\right)\)
\(=\left(3x+1\right)\left(4x^2-9\right)\)
\(=\left(3x+1\right)\left(2x-3\right)\left(2x+3\right)\)
\(4x^4+4x^3-x^2-x\)
\(=4x^3\left(x+1\right)-x\left(x+1\right)\)
\(=x\left(x+1\right)\left(4x^2-1\right)\)
\(=x\left(x+1\right)\left(2x-1\right)\left(2x+1\right)\)
Dạng 3 :
a) 3x - 10 = 2x + 13
=> 3x - 2x = 13 - 10
=> x = 3
b) x + 12 = -5 - x
=> x + x = -5 - 12
=> 2x = -17
=> x = -8,5
c) x + 5 = 10 - x
=> x + x = 10 - 5
=> 2x = 5
=> x = 2,5
d) 6x + 23 = 2x - 12
=> 2x - 6x = 23 + 12
=> -4x = 35
=> x = -8,75
e) 12 - x = x + 1
=> x + x = 12 - 1
=> 2x = 11
=> x = 5,5
f) 14 + 4x = 3x + 20
=> 4x - 3x = 20 - 14
=> x = 6
Cộng các tổng ở các mẫu số được: \(S=1+\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+\frac{1}{28}+\frac{1}{36}.\)
\(\Leftrightarrow S=1+\frac{1}{2}\left(1-\frac{1}{3}\right)+\frac{1}{6}+\frac{1}{10}+\frac{1}{2}\left(\frac{1}{3}-\frac{1}{5}\right)+\frac{1}{21}+\frac{1}{3}\left(\frac{1}{4}-\frac{1}{7}\right)+\frac{1}{36}.\)
Thực hiện các phép nhân một số với một hiệu ,được:
\(S=1+\frac{1}{2}-\frac{1}{6}+\frac{1}{6}+\frac{1}{10}+\frac{1}{6}-\frac{1}{15}+\frac{1}{21}+\frac{1}{12}-\frac{1}{21}+\frac{1}{36}.\)
Giản ước, làm gọn được : \(S=(1+\frac{1}{2})+(\frac{1}{10}+\frac{1}{6}-\frac{1}{15})+(\frac{1}{12}+\frac{1}{36}).\)
\(\Leftrightarrow S=\frac{3}{2}+\frac{1}{5}+\frac{1}{9}=\frac{135+18+10}{90}=\frac{163}{90}.\)
q, bạn ghi đề rõ nhé
s, \(\dfrac{2}{3}x=\dfrac{1}{2}-\dfrac{7}{12}=\dfrac{-1}{12}\Leftrightarrow x=-\dfrac{1}{12}:\dfrac{2}{3}=-\dfrac{3}{24}=-\dfrac{1}{8}\)
t, \(\dfrac{3}{4}x=\dfrac{1}{6}-\dfrac{1}{5}=\dfrac{-1}{30}\Leftrightarrow x=-\dfrac{1}{30}:\dfrac{3}{4}=-\dfrac{4}{90}=-\dfrac{2}{45}\)
u, \(\dfrac{1}{6}x=\dfrac{3}{8}-\dfrac{1}{4}=\dfrac{1}{8}\Leftrightarrow x=\dfrac{1}{8}:\dfrac{1}{6}=\dfrac{6}{8}=\dfrac{3}{4}\)
s, 23x=12−712=−112⇔x=−112:23=−324=−1823x=12−712=−112⇔x=−112:23=−324=−18
t, 34x=16−15=−130⇔x=−130:34=−490=−24534x=16−15=−130⇔x=−130:34=−490=−245
u, 16x=38−14=18⇔x=18:16=68=34
HT