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28 tháng 11 2016

\(8-12x+6x^2-x^3\)

\(=\left(2-x\right)^3\)

\(125x^3-75x^2+15x-1\)

\(=\left(5x-1\right)^3\)

\(x^2-xz-9y^2+3yz\)

\(=\left(x-3y\right)\left(x+3y\right)-z\left(x-3y\right)\)

\(=\left(x-3y\right)\left(x+3y-z\right)\)

\(x^3-x^2-5x+125\)

\(=\left(x+5\right)\left(x^2-5x+25\right)-x\left(x+5\right)\)

\(=\left(x+5\right)\left(x^2-5x+25-x\right)\)

\(=\left(x+5\right)\left(x^2-6x+25\right)\)

\(x^3+2x^2-6x-27\)

\(=x^3+5x^2+9x-3x^2-15x-27\)

\(=x\left(x^2+5x+9\right)-3\left(x^2+5x+9\right)\)

\(=\left(x-3\right)\left(x^2+5x+9\right)\)

\(12x^3+4x^2-27x-9\)

\(=4x^2\left(3x+1\right)-9\left(3x+1\right)\)

\(=\left(3x+1\right)\left(4x^2-9\right)\)

\(=\left(3x+1\right)\left(2x-3\right)\left(2x+3\right)\)

\(4x^4+4x^3-x^2-x\)

\(=4x^3\left(x+1\right)-x\left(x+1\right)\)

\(=x\left(x+1\right)\left(4x^2-1\right)\)

\(=x\left(x+1\right)\left(2x-1\right)\left(2x+1\right)\)

8 tháng 4 2018

a) \(\frac{9}{20}\)                                                   c) \(\frac{-55}{4}\)                                                                                                                                 

b) \(\frac{116}{75}\)                                                d) \(\frac{-76}{45}\)

đúng hết đấy nhé mình tính kĩ lắm ko sai đâu

       chúc may mắn

18 tháng 7 2016

c) pt <=> \(x-\frac{21}{5}=\frac{23}{7}< =>x=\frac{23}{7}+\frac{21}{5}=\frac{262}{35}\)

vậy x = \(\frac{262}{35}\) 

d) \(x-\frac{3}{4}=\frac{51}{8}< =>x=\frac{51}{8}+\frac{3}{4}=\frac{57}{8}\) 

vậy x = \(\frac{57}{8}\) 

e) pt <=> \(\frac{7}{8}:x=\frac{7}{2}< =>\frac{7}{8}.\frac{1}{x}=\frac{7}{2}< =>\frac{7}{8x}=\frac{7}{2}< =>56x=14< =>x=\frac{14}{56}=\frac{1}{4}\)

vậy x = \(\frac{1}{4}\)

18 tháng 7 2016

a) pt <=> \(x+\frac{11}{4}=\frac{17}{3}< =>x=\frac{17}{3}-\frac{11}{4}=\frac{35}{12}\)

vậy x = \(\frac{35}{12}\)

b) pt <=> \(\frac{x.7}{2}=\frac{19}{4}< =>x=\frac{19.2}{4.7}=\frac{38}{28}=\frac{19}{14}\)

vậy x = \(\frac{19}{14}\) 

 

27 tháng 11 2018

a, \(2.x^x=10.3^{12}+8.27^4\)

\(2.x^x=10.3^{12}+8.3^{12}\)

\(2.x^x=3^{12}.\left(10+8\right)\)

\(2.x^x=3^{12}.18\)

\(2.x^x=3^{12}.2.3^3\)

\(2.x^x=3^{15}.2\)

\(x^x=3^{15}\)( Hình như sai đề )

b,\(3^{2x+2}=9^{x+3}\)

\(3^{2x+2}=3^{2x+3}\)

27 tháng 11 2018

câu b Sai đề

26 tháng 7 2019

a) \(x+\frac{5}{12}=-1\frac{2}{7}\)

\(\Leftrightarrow x+\frac{5}{12}=\frac{-9}{7}\)

\(\Leftrightarrow x=\frac{-143}{84}\)

Vậy ...

b) \(4\frac{1}{2}x:\frac{5}{12}=0,5\)

\(\Leftrightarrow\frac{9}{2}x=\frac{5}{24}\)

\(\Leftrightarrow x=\frac{5}{108}\)

vậy...

c) \(7,5.1\frac{3}{4}x=6\frac{2}{5}\)

\(\Leftrightarrow\frac{105}{8}x=\frac{32}{5}\)

\(\Leftrightarrow x=\frac{256}{525}\)

Vậy ...

27 tháng 6 2018

c) \(\dfrac{x+1}{35}+\dfrac{x+2}{34}+\dfrac{x+3}{33}=\dfrac{x+4}{32}+\dfrac{x+5}{31}+\dfrac{x+6}{30}\)

\(\Rightarrow\dfrac{x+1}{35}+1+\dfrac{x+2}{34}+1+\dfrac{x+3}{33}+1=\dfrac{x+4}{32}+1+\dfrac{x+5}{31}+1+\dfrac{x+6}{30}+1\)

\(\Rightarrow\dfrac{x+1+35}{35}+\dfrac{x+2+34}{34}+\dfrac{x+3+33}{33}=\dfrac{x+4+32}{32}+\dfrac{x+5+31}{31}+\dfrac{x+6+30}{30}\)

\(\Rightarrow\dfrac{x+36}{35}+\dfrac{x+36}{34}+\dfrac{x+36}{33}=\dfrac{x+36}{32}+\dfrac{x+36}{31}+\dfrac{x+36}{30}\)

\(\Rightarrow\dfrac{x+36}{35}+\dfrac{x+36}{34}+\dfrac{x+36}{33}-\dfrac{x+36}{32}-\dfrac{x+36}{31}-\dfrac{x+36}{30}=0\)

\(\Rightarrow\left(x+36\right)\left(\dfrac{1}{35}+\dfrac{1}{34}+\dfrac{1}{33}+\dfrac{1}{32}+\dfrac{1}{31}+\dfrac{1}{30}\right)=0\)

\(\Rightarrow x+36=0\left(\text{vì }\dfrac{1}{35}+\dfrac{1}{34}+\dfrac{1}{33}+\dfrac{1}{32}+\dfrac{1}{31}+\dfrac{1}{30}\ne0\right)\)

\(\Rightarrow x=-36\)

Vậy ...

27 tháng 6 2018

a/ Ta có: \(-4\dfrac{3}{5}.2\dfrac{4}{3}\le x\le-2\dfrac{3}{5}:1\dfrac{6}{15}\)

\(\Rightarrow\dfrac{-23}{5}.\dfrac{10}{3}\le x\le\dfrac{-13}{5}:\dfrac{21}{15}\)

\(\Rightarrow\dfrac{-46}{3}\le x\le\dfrac{-13}{5}.\dfrac{15}{21}\)

\(\Rightarrow\dfrac{-46}{3}\le x\le\dfrac{-13}{7}\)

\(\Rightarrow-15,\left(3\right)\le x\le-1,\left(857142\right)\)

Vì x \(\in\) Z nên x \(\in\left\{-1;-2;-3;...;-15\right\}\)

Chúc bạn học tốt!!!okokok

11 tháng 8 2020

a,\(x-\frac{1}{2}=\frac{3}{4}\)

\(< =>x=\frac{3}{4}+\frac{1}{2}=\frac{5}{4}\)

b,\(2x-\frac{1}{3}=\frac{5}{6}\)

\(< =>2x=\frac{5}{6}+\frac{1}{3}\)

\(< =>2x=\frac{7}{6}\)

\(< =>x=\frac{7}{12}\)

c, \(\frac{7}{4}-|x-1|=\frac{1}{2}\)

\(< =>|x-1|=\frac{7}{4}-\frac{2}{4}=\frac{5}{4}\)

\(< =>\orbr{\begin{cases}x-1=\frac{5}{4}\\x-1=-\frac{5}{4}\end{cases}}\)

\(< =>\orbr{\begin{cases}x=\frac{9}{4}\\x=-\frac{1}{4}\end{cases}}\)

11 tháng 8 2020

\(a,x-\frac{1}{2}=\frac{3}{4}\)

\(x=\frac{3}{4}+\frac{1}{2}\)

\(x=\frac{5}{4}\)

\(b,2x-\frac{1}{3}=\frac{5}{6}\)

\(2x=\frac{5}{6}+\frac{1}{3}\)

\(2x=\frac{7}{6}\)

\(x=\frac{7}{6}:2\)

\(x=\frac{7}{12}\)

\(c,\frac{7}{4}-|x-1|=\frac{1}{2}\)

\(|x-1|=\frac{7}{4}-\frac{1}{2}\)

\(|x-1|=\frac{5}{4}\)

\(\Rightarrow\orbr{\begin{cases}x-1=\frac{5}{4}\\x-1=\frac{-5}{4}\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{9}{4}\\x=\frac{-1}{4}\end{cases}}\)

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