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8 tháng 4 2018

a) \(\frac{148-x}{25}+\frac{169-x}{23}+\frac{186-x}{21}+\frac{199-x}{19}=10\)

\(\Leftrightarrow\left(\frac{148-x}{25}-1\right)+\left(\frac{169-x}{23}-2\right)+\left(\frac{186-x}{21}-3\right)+\left(\frac{199-x}{19}-4\right)=0\)

\(\Leftrightarrow\frac{123-x}{25}+\frac{123-x}{23}+\frac{123-x}{21}+\frac{123-x}{19}=0\)

\(\Leftrightarrow\left(123-x\right)\left(\frac{1}{25}+\frac{1}{23}+\frac{1}{21}+\frac{1}{19}\right)=0\)

\(\Leftrightarrow x=123\)

c) \(x^4-10.2^x+16=0\)

\(\Leftrightarrow\left(2^x\right)^2-10.2^x+16=0\)

Ta có: 

\(2^x=t\)

\(\Rightarrow t^2-10t+16=0\)

\(\Leftrightarrow\orbr{\begin{cases}t=8\\t=2\end{cases}}\Rightarrow\orbr{\begin{cases}x=3\\x=1\end{cases}}\)

18 tháng 2 2020

Bạn xem lại có sai đề ko,mk thấy sao sao ý

18 tháng 2 2020

sai j mà sai...k lm đc thì có

3 tháng 1 2021

a) 3x - 2(5 + 2x) =45 - 2x

=> 3x - 10 - 4x = 45 - 2x

=> 3x - 4x + 2x = 45 + 10

=> x = 55

b) \(\frac{x-3}{5}=6-\frac{1-2x}{3}\)

=> \(\frac{x-3}{5}=\frac{2x+17}{3}\)

=> 5(2x + 17) = 3(x - 3)

=> 10x + 85 = 3x - 9

=> 7x = -94

=> x = -94/7

c) \(\frac{5\left(x-1\right)+2}{6}-\frac{7x-1}{4}=\frac{2\left(2x+1\right)}{7}-5\)

=> \(\frac{5x-3}{6}-\frac{7x-1}{4}=\frac{4x-33}{7}\)

=> \(\frac{10x-6}{12}-\frac{21x-3}{12}=\frac{4x-33}{7}\)

=> \(\frac{-11x-3}{12}=\frac{4x-33}{7}\)

=> (-11x - 3).7 = (4x - 33).12

= -77x - 21 = 48x - 396

=> x = 3

d) (x - 1)(5x + 3) = (3x - 8)(x - 1)

=> (x - 1)(5x + 3) - (3x - 8)(x -1) = 0

=> (x - 1)(2x + 11) = 0

=> \(\orbr{\begin{cases}x-1=0\\2x+11=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=1\\x=-5,5\end{cases}}\) 

e) (x - 1)(x2 + 5x - 2) - (x3 - 1) = 0

=> (x - 1)(x2 + 5x - 2) - (x - 1)(x2 + x + 1) = 0

=> (x - 1)(4x - 3) = 0

=> \(\orbr{\begin{cases}x-1=0\\4x-3=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=1\\x=0,75\end{cases}}\)

f) \(\frac{x-17}{33}+\frac{x-21}{29}+\frac{x}{25}=4\) 

=> \(\left(\frac{x-17}{33}-1\right)+\left(\frac{x-21}{29}-1\right)+\left(\frac{x}{25}-2\right)=0\)

=> \(\frac{x-50}{33}+\frac{x-50}{29}+\frac{x-50}{25}=0\)

=> \(\left(x-50\right)\left(\frac{1}{33}+\frac{1}{29}+\frac{1}{25}\right)=0\)

=> x - 50 = 0 (Vì \(\frac{1}{33}+\frac{1}{29}+\frac{1}{25}\ne0\))

=> x = 50

3 tháng 1 2021

b, \(\frac{x-3}{5}=6-\frac{1-2x}{3}\)

\(\Leftrightarrow\frac{x-3}{5}=\frac{17+2x}{3}\Leftrightarrow3x-9=85+10x\)

\(\Leftrightarrow-7x=94\Leftrightarrow x=-\frac{94}{7}\)

f, sửa : \(\frac{x+1}{65}+\frac{x+3}{63}=\frac{x+5}{61}+\frac{x+7}{59}\)

\(\Leftrightarrow\frac{x+1}{65}+1+\frac{x+3}{63}+1=\frac{x+5}{61}+1+\frac{x+7}{59}+1\)

\(\Leftrightarrow\frac{x+66}{65}+\frac{x+66}{63}=\frac{x+66}{61}+\frac{x+66}{59}\)

\(\Leftrightarrow\frac{x+66}{65}+\frac{x+66}{63}-\frac{x+66}{61}-\frac{x+66}{59}=0\)

\(\Leftrightarrow\left(x+66\right)\left(\frac{1}{65}+\frac{1}{63}-\frac{1}{61}-\frac{1}{59}\ne0\right)=0\)

\(\Leftrightarrow x=-66\)

7 tháng 8 2016

Mk chi p bang 123 vi bam may tinh, con ck jai thi hk p!

7 tháng 8 2016

CÁM ƠN bn tuy chưa có lời jai n cx đk

18 tháng 1 2018

\(\Leftrightarrow\frac{148-x}{25}-1+\frac{169-x}{23}-2+\frac{186-x}{21}-3+\frac{199-x}{19}-4=0\)

\(\Leftrightarrow\frac{123-x}{25}+\frac{123-x}{23}+\frac{123-x}{21}+\frac{123-x}{19}=0\)

\(\Leftrightarrow\left(123-x\right)\left(\frac{1}{25}+\frac{1}{23}+\frac{1}{21}+\frac{1}{19}\right)=0\)

Mà \(\frac{1}{25}+\frac{1}{23}+\frac{1}{21}+\frac{1}{19}\ne0\)

\(\Rightarrow123-x=0\Rightarrow x=123\)

Vậy Tập nghiệm của phương trình là \(S=\left\{123\right\}\)

18 tháng 1 2018

<=> 148-×/25 -1 + 169-x/23 -2 + 186-x/21 - 3 + 199-×/19 - 4=0  

<=>  (123-x)(1/25+1/23+1/21+1/19)=0

<=> x=123

Chúc bạn học tốt

14 tháng 1 2016

\(\frac{148-x}{25}+\frac{169-x}{23}+\frac{186-x}{21}+\frac{199-x}{19}=10\)

\(\Leftrightarrow\frac{148-x}{25}-1+\frac{169-x}{23}-2+\frac{186-x}{21}-3+\frac{199-x}{19}-4=0\)

\(\Leftrightarrow\frac{148-x}{25}-\frac{25}{25}+\frac{169-x}{23}-\frac{46}{23}+\frac{186-x}{21}-\frac{63}{21}+\frac{199-x}{19}-\frac{76}{19}=0\)

\(\Leftrightarrow\frac{123-x}{25}+\frac{123-x}{23}+\frac{123-x}{21}+\frac{123-x}{19}=0\)

\(\Leftrightarrow\left(123-x\right).\left(\frac{1}{25}+\frac{1}{23}+\frac{1}{21}+\frac{1}{19}\right)=0\)

\(\Leftrightarrow123-x=0\left(\text{vì }\frac{1}{25}+\frac{1}{23}+\frac{1}{21}+\frac{1}{19}\ne0\right)\)

<=>x=123

Vậy S={123}

19 tháng 6 2019

\(a,\)( sửa lại xíu đề cho đúng nhé )

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

\(\Rightarrow\frac{x^2+x+1}{\left(x-1\right)\left(x^2+x+1\right)}-\frac{3x^2}{\left(x-1\right)\left(x^2+x+1\right)}=-\frac{2x\left(x-1\right)}{\left(x-1\right)\left(x^2+x+1\right)}\)

\(\Rightarrow x^2+x+1-3x^2=-2x^2+2x\)

\(\Rightarrow x=1\)

19 tháng 6 2019

\(g,\)\(\left(x+2\right)\left(x+4\right)\left(x+6\right)\left(x+8\right)=-16\)

\(\Rightarrow\left(x^2+10x+16\right)\left(x^2+10x+24\right)=-16\)

Đặt \(x^2+10x+16=a\)

\(\Rightarrow a\left(a+8\right)=-16\)

\(\Rightarrow a^2+8a+16=0\)

\(\Rightarrow\left(a+4\right)^2=0\)

\(\Leftrightarrow\left(x^2+10x+20\right)^2=0\)

\(\Rightarrow x^2+10x+25-25=0\)

\(\Rightarrow\left(x+5\right)^2-\left(\sqrt{5}\right)^2=0\)

\(\Rightarrow\left(x+5-\sqrt{5}\right)\left(x+5+\sqrt{5}\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x=-5+\sqrt{5}\\x=-5-\sqrt{5}\end{cases}}\)

16 tháng 2 2017

\(\frac{148-x}{13}-1+\frac{169-x}{17}-2+\frac{186-x}{17}-3+\frac{199-x}{16}-4=0\)\(\frac{135-x}{13}+\frac{135-x}{17}+\frac{135-x}{17}+\frac{135-x}{16}=0\)

(135-x)(\(\frac{1}{13}+\frac{1}{17}+\frac{1}{17}+\frac{1}{16}\))=0

135-x=0

x=135

16 tháng 2 2017

Có : \(\frac{148-x}{13}+\frac{169-x}{17}+\frac{186-x}{17}+\frac{199-x}{16}=10\)

\(\Leftrightarrow\)\(\left(\frac{148-x}{13}-1\right)+\)\(\left(\frac{169-x}{17}-2\right)+\)\(\left(\frac{186-x}{17}-3\right)\) + \(\left(\frac{199-x}{16}-4\right)=10\)

\(\Leftrightarrow\) \(\frac{135-x}{13}+\frac{135-x}{17}+\frac{135-x}{17}+\frac{135-x}{16}\)= 10

\(\Leftrightarrow\) \(\left(135-x\right)\left(\frac{1}{13}+\frac{1}{17}+\frac{1}{17}+\frac{1}{16}\right)=0\)

\(\Leftrightarrow\) \(135-x=0\) \(\left(\frac{1}{13}+\frac{1}{17}+\frac{1}{17}+\frac{1}{16}\right)\ne0\)

\(\Leftrightarrow\) \(x=135\)

Vậy \(x=135\)

ok