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Ta có : \(\frac{6}{x^2-9}=1-\frac{1}{3-x}\) (đk : x khác 3;-3)_

\(\Leftrightarrow\frac{6}{x^2-9}+\frac{1}{3-x}-1=0\)

\(\Leftrightarrow\frac{6}{x^2-9}-\frac{1}{x-3}-1=0\)

\(\Leftrightarrow\frac{6}{x^2-9}-\frac{x+3}{x^2-9}-\frac{x^2-9}{x^2-9}=0\)

\(\Leftrightarrow\frac{6-x-3-x^2+9}{x^2-9}=0\)

\(\Leftrightarrow\frac{-x^2-x+12}{x^2-9}=0\)

\(\Leftrightarrow\frac{-x^2+3x-4x+12}{x^2-9}=0\)

\(\Leftrightarrow\frac{x\left(x-3\right)-4\left(x-3\right)}{x^2-9}=0\)

\(\Leftrightarrow\frac{\left(x-4\right)\left(x-3\right)}{x^2-9}=0\)

\(\Leftrightarrow\frac{x-4}{x+3}=0\)

<=> x - 4 = 0

<=> x = 4 (t/m)

2 tháng 3 2020

\(M=\left(x-1\right)\left(x+2\right)\left(x+3\right)\left(x+6\right)\)

\(=\left(x-1\right)\left(x+6\right)\left(x+2\right)\left(x+3\right)\)

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

\(=\left(x^2+5x\right)^2-36\ge-36\)

Dấu "=" xảy ra khi \(x\in\left\{0;-5\right\}\)

2 tháng 3 2020

Giải PT \(\frac{x-6}{2010}+\frac{x-603}{471}+\frac{x-1}{403}=9\)

\(\Leftrightarrow\frac{x-6}{2010}+\frac{x-603}{471}+\frac{x-1}{403}-9=0\)

\(\Leftrightarrow\left(\frac{x-6}{2010}-1\right)+\left(\frac{x-603}{471}-3\right)+\left(\frac{x-1}{403}-5\right)=0\)

\(\Leftrightarrow\frac{x-2016}{2010}+\frac{x-2016}{471}+\frac{x-2016}{403}=0\)

\(\Leftrightarrow\left(x-2016\right)\left(\frac{1}{2010}+\frac{1}{471}+\frac{1}{403}\right)=0\)

Mà \(\left(\frac{1}{2010}+\frac{1}{471}+\frac{1}{403}\right)\ne0\)

\(\Leftrightarrow x-2016=0\Leftrightarrow x=2016\)

Vậy x=2016

b) \(M=\left(x-1\right)\left(x+2\right).\left(x+3\right)\left(x+6\right)\)

\(M=\left[\left(x-1\right)\left(x+6\right)\right].\left[\left(x+2\right).\left(x+3\right)\right]\)

\(M=\left(x^2+5x-6\right).\left(x^2+5x+6\right)=\left(x^2+5x\right)^2-36\)

Các bạn tự làm tiếp được rồi nhé

a) ĐKXĐ: x≠0

Ta có: \(\frac{9}{x}+2=-6\)

\(\frac{9}{x}+2+6=0\)

\(\frac{9}{x}+8=0\)

\(\frac{9}{x}+\frac{8x}{x}=0\)

⇔9+8x=0

⇔8x=-9

hay \(x=-\frac{9}{8}\)

Vậy: \(x=-\frac{9}{8}\)

b) ĐKXĐ: x≠0;x≠-1;x≠-3

Ta có: \(\frac{7}{x+1}+\frac{-18x}{x\left(x^2+4x+3\right)}=\frac{-4}{x+3}\)

\(\frac{7}{x+1}+\frac{-18x}{x\left(x+1\right)\left(x+3\right)}-\frac{-4}{x+3}=0\)

\(\frac{7x\left(x+3\right)}{\left(x+1\right)\cdot x\cdot\left(x+3\right)}+\frac{-18x}{\left(x+1\right)\cdot x\cdot\left(x+3\right)}-\frac{-4x\left(x+1\right)}{\left(x+3\right)\cdot x\cdot\left(x+1\right)}=0\)

\(7x^2+21x-18x+4x\left(x+1\right)=0\)

\(\Leftrightarrow7x^2+21x-18x+4x^2+4x=0\)

\(11x^2+7x=0\)

\(\Leftrightarrow x\left(11x+7\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\11x+7=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\11x=-7\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\left(loại\right)\\x=\frac{-7}{11}\end{matrix}\right.\)

Vậy: \(x=\frac{-7}{11}\)

c) ĐKXĐ: x≠1; x≠-3

Ta có: \(\frac{3x-1}{x-1}-1=\frac{2x+5}{x+3}+\frac{4}{x^2-2x+3}\)

\(\frac{3x-1}{x-1}-1-\frac{2x+5}{x+3}-\frac{4}{\left(x-1\right)\left(x+3\right)}=0\)

\(\frac{\left(3x-1\right)\left(x+3\right)}{\left(x-1\right)\left(x+3\right)}-\frac{\left(x-1\right)\left(x+3\right)}{\left(x-1\right)\left(x+3\right)}-\frac{\left(2x+5\right)\left(x-1\right)}{\left(x+3\right)\left(x-1\right)}-\frac{4}{\left(x-1\right)\left(x+3\right)}=0\)

\(\left(3x-1\right)\left(x+3\right)-\left(x-1\right)\left(x+3\right)-\left(2x+5\right)\left(x-1\right)-4=0\)

\(\Leftrightarrow3x^2+9x-x-3-\left(x^2+3x-x-3\right)-\left(2x^2-2x+5x-5\right)-4=0\)

\(\Leftrightarrow3x^2+8x-3-\left(x^2+2x-3\right)-\left(2x^2+3x-5\right)-4=0\)

\(\Leftrightarrow3x^2+8x-3-x^2-2x+3-2x^2-3x+5-4=0\)

\(\Leftrightarrow3x+1=0\)

\(\Leftrightarrow3x=-1\)

hay \(x=\frac{-1}{3}\)

Vậy: \(x=\frac{-1}{3}\)

27 tháng 2 2020

1/ \(\frac{3\left(x+3\right)}{4}+\frac{1}{2}=\frac{5x+9}{3}-\frac{7x-9}{4}\)

=> \(\frac{9\left(x+3\right)}{12}+\frac{6}{12}=\frac{4\left(5x+9\right)}{12}-\frac{3\left(7x-9\right)}{12}\)

=> \(9\left(x+3\right)+6=4\left(5x+9\right)-3\left(7x-9\right)\)

=> \(9x+27+6=20x+36-21x+27\)

=> \(9x-20x+21x=27-27-6+36\)

=> \(10x=30\)

=> \(x=3\)

Vậy phương trình có tập nghiệm là \(S=\left\{3\right\}\)

2.Ta có : \(\frac{2x-3}{3}-\frac{x-3}{6}=\frac{4x+3}{5}-17\)

=> \(\frac{10\left(2x-3\right)}{30}-\frac{5\left(x-3\right)}{30}=\frac{6\left(4x+3\right)}{30}-\frac{510}{30}\)

=> \(10\left(2x-3\right)-5\left(x-3\right)=6\left(4x+3\right)-510\)

=> \(20x-30-5x+15=24x+18-510\)

=> \(20x-5x-24x=18-510+30-15\)

=> \(-9x=-477\)

=> \(x=53\)

Vậy phương trình có tập nghiệm là \(S=\left\{53\right\}\)

3/ Ta có : \(\frac{5x-1}{6}+\frac{2\left(x+4\right)}{9}=\frac{7x-5}{15}+x-1\)

=> \(\frac{30\left(5x-1\right)}{180}+\frac{40\left(x+4\right)}{180}=\frac{12\left(7x-5\right)}{180}+\frac{180x}{180}-\frac{180}{180}\)

=> \(30\left(5x-1\right)+40\left(x+4\right)=12\left(7x-5\right)+180x-180\)

=> \(150x-30+40x+160=84x-60+180x-180\)

=> \(150x+40x-180x-84x=-60-180-160+30\)

=> \(-74x=-370\)

=> \(x=5\)

Vậy phương trình có tập nghiệm là \(S=\left\{5\right\}\)

27 tháng 2 2020

cảm ơn nha

Bài 1: 

a: \(\Leftrightarrow\left(x-1\right)\left(x-3\right)-x\left(x+3\right)=-7x+3\)

\(\Leftrightarrow x^2-4x+3-x^2-3x+7x-3=0\)

=>0x=0(luôn đúng)

Vậy: S={x|\(x\notin\left\{3;-3\right\}\)}

b: \(\Leftrightarrow2x+3< 6-3+4x\)

=>2x+3<4x+3

=>-2x<0

hay x>0

7 tháng 3 2020

a) \(pt\Leftrightarrow\frac{6}{x^2+2}-1+\frac{7}{x^2+3}-1+\frac{12}{x^2+8}-1-\frac{3x^2+16}{x^2+10}+2=0\)

\(\Leftrightarrow\frac{4-x^2}{x^2+2}+\frac{4-x^2}{x^2+3}+\frac{4-x^2}{x^2+8}+\frac{4-x^2}{x^2+10}=0\)

\(\Leftrightarrow\left(4-x^2\right)\left(\frac{1}{x^2+2}+\frac{1}{x^2+3}+\frac{1}{x^2+8}+\frac{1}{x^2+10}\right)=0\)

\(\Leftrightarrow4-x^2=0\)(do \(\frac{1}{x^2+2}+\frac{1}{x^2+3}+\frac{1}{x^2+8}+\frac{1}{x^2+10}>0,\forall x\))

\(\Leftrightarrow x^2=4\Leftrightarrow x=\pm2\)

\(KL...\)

7 tháng 3 2020

2x(8x - 1)2(4x - 1) = 9

<=> 512x4 - 256x3 + 40x2 - 2x = 9

<=> 512x4 - 256x3 + 40x2 - 2x - 9 = 0

<=> (2x - 1)(4x + 1)(64x4 - 16x + 9) = 0

vì 64x4 - 16x + 9 khác 0 nên:

<=> 2x - 1 = 0 hoặc 4x + 1 = 0

<=> x = 1/2 hoặc x = -1/4

6 tháng 2 2017

1) Nhìn cái pt hết ham, nhưng bấm nghiệm đẹp v~`~

\(\left(\sqrt{2}+2\right)\left(x\sqrt{2}-1\right)=2x\sqrt{2}-\sqrt{2}\)

\(\Leftrightarrow\left(\sqrt{2}+2\right)\left(x\sqrt{2}-1\right)-2x\sqrt{2}+\sqrt{2}=0\)

\(\Leftrightarrow2x-\sqrt{2}+2x\sqrt{2}-2-2x\sqrt{2}+\sqrt{2}=0\)

\(\Leftrightarrow2x-2=0\Leftrightarrow2x=2\Rightarrow x=1\)

6 tháng 2 2017

Mấy bài kia sao cái phương trình dài thê,s giải sao nổi

1) Ta có: x-4=2x+4

\(\Leftrightarrow x-4-2x-4=0\)

\(\Leftrightarrow-x-8=0\)

\(\Leftrightarrow-x=8\)

hay x=-8

Vậy: S={8}

2) Ta có: \(\frac{2x-1}{2}-\frac{x}{3}=x-\frac{x}{6}\)

\(\Leftrightarrow\frac{3\left(2x-1\right)}{6}-\frac{2x}{6}=\frac{6x}{6}-\frac{x}{6}\)

\(\Leftrightarrow3\left(2x-1\right)-2x-6x+x=0\)

\(\Leftrightarrow6x-3-2x-6x+x=0\)

\(\Leftrightarrow-x-3=0\)

\(\Leftrightarrow-x=3\)

hay x=-3

Vậy: S={-3}

3) ĐKXĐ: \(x\notin\left\{\frac{-1}{2};3\right\}\)

Ta có: \(\frac{x+3}{2x+1}-\frac{x}{x-3}=\frac{3x^2+x+9}{\left(2x+1\right)\left(x-3\right)}\)

\(\Leftrightarrow\frac{\left(x+3\right)\left(x-3\right)}{\left(2x+1\right)\left(x-3\right)}-\frac{x\left(2x+1\right)}{\left(x-3\right)\left(2x+1\right)}=\frac{3x^2+x+9}{\left(2x+1\right)\left(x-3\right)}\)

Suy ra: \(x^2-9-\left(2x^2+x\right)-3x^2-x-9=0\)

\(\Leftrightarrow-2x^2-x-18-2x^2-x=0\)

\(\Leftrightarrow-4x^2-2x-18=0\)

\(\Leftrightarrow-4\left(x^2+\frac{1}{2}x+\frac{4}{5}\right)=0\)

\(\Leftrightarrow x^2+\frac{1}{2}x+\frac{4}{5}=0\)

\(\Leftrightarrow x^2+2\cdot x\cdot\frac{1}{4}+\frac{1}{16}+\frac{59}{80}=0\)

\(\Leftrightarrow\left(x+\frac{1}{4}\right)^2+\frac{59}{80}=0\)(vô lý)

Vậy: S=\(\varnothing\)

4) Ta có: \(\frac{2x}{3}+\frac{2x-1}{6}=4-\frac{x}{3}\)

\(\Leftrightarrow\frac{4x}{6}+\frac{2x-1}{6}=\frac{24}{6}-\frac{2x}{6}\)

\(\Leftrightarrow4x+2x-1=24-2x\)

\(\Leftrightarrow6x-1-24+2x=0\)

\(\Leftrightarrow8x-25=0\)

\(\Leftrightarrow8x=25\)

hay \(x=\frac{25}{8}\)

Vậy: \(S=\left\{\frac{25}{8}\right\}\)

NV
12 tháng 3 2019

\(\frac{1}{x^2-2x+2}-1+\frac{2}{x^2-2x+3}-1+2-\frac{6}{x^2-2x+4}=0\)

\(\Leftrightarrow\frac{-x^2+2x-1}{x^2-2x+2}+\frac{-x^2+2x-1}{x^2-2x+3}+\frac{2\left(x^2-2x+1\right)}{x^2-2x+4}=0\)

\(\Leftrightarrow\left(x^2-2x+1\right)\left(\frac{2}{x^2-2x+4}-\frac{1}{x^2-2x+2}-\frac{1}{x^2-2x+3}\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x^2-2x+1=0\Rightarrow x=1\\\frac{2}{x^2-2x+4}-\frac{1}{x^2-2x+2}-\frac{1}{x^2-2x+3}=0\left(1\right)\end{matrix}\right.\)

Xét (1), đặt \(a=x^2-2x+3\) pt trở thành:

\(\frac{2}{a+1}-\frac{1}{a-1}-\frac{1}{a}=0\Leftrightarrow\frac{2\left(a-1\right)-\left(a+1\right)}{\left(a^2-1\right)}-\frac{1}{a}=0\)

\(\Leftrightarrow\frac{a-3}{a^2-1}=\frac{1}{a}\Leftrightarrow a^2-3a=a^2-1\Leftrightarrow3a=1\Rightarrow a=\frac{1}{3}\)

\(\Rightarrow x^2-2x+3=\frac{1}{3}\Leftrightarrow x^2-2x+1+\frac{5}{3}=0\)

\(\Leftrightarrow\left(x-1\right)^2+\frac{5}{3}=0\) (vô nghiệm)

Vậy \(x=1\)

12 tháng 3 2019

\(\left(x-1\right)^2+\frac{5}{3}=0\) (ko thỏa đk )

ms đúng. chứ vẫn có no mà!!

1 tháng 6 2020

\(\frac{3x+2}{x+4}+\frac{2x+1}{x-2}=5-\frac{x-32}{x^2+2x-8}\)

\(\Leftrightarrow\) \(\frac{\left(3x+2\right)\left(x-2\right)}{\left(x+4\right)\left(x-2\right)}+\frac{\left(2x+1\right)\left(x+4\right)}{\left(x+4\right)\left(x-2\right)}=\frac{5\left(x+4\right)\left(x-2\right)}{\left(x+4\right)\left(x-2\right)}-\frac{x-32}{\left(x+4\right)\left(x-2\right)}\)

\(\Rightarrow\) (3x + 2)(x - 2) + (2x + 1)(x + 4) = 5(x + 4)(x - 2) - x + 32

\(\Leftrightarrow\) 3x2 - 6x + 2x - 4 + 2x2 + 8x + x + 4 = 5x2 - 10x + 20x - 40 - x + 32

\(\Leftrightarrow\) 5x2 + 5x = 5x2 + 9x - 8

\(\Leftrightarrow\) 5x2 + 5x - 5x2 - 9x + 8 = 0

\(\Leftrightarrow\) -4x + 8 = 0

\(\Leftrightarrow\) x - 2 = 0

\(\Leftrightarrow\) x = 2

Vậy S = {2}

\(\frac{x+2m}{x+3}+\frac{x-m}{x-3}=\frac{mx\left(x+1\right)}{x^2-9}\) (đkxđ: x \(\ne\) \(\pm\) 3)

\(\Leftrightarrow\) \(\frac{\left(x+2m\right)\left(x-3\right)}{\left(x+3\right)\left(x-3\right)}+\frac{\left(x-m\right)\left(x+3\right)}{\left(x+3\right)\left(x-3\right)}=\frac{mx\left(x+1\right)}{\left(x+3\right)\left(x-3\right)}\)

\(\Rightarrow\) (x + 2m)(x - 3) + (x - m)(x + 3) = mx(x + 1)

\(\Leftrightarrow\) x2 - 3x + 2mx - 6m + x2 + 3x - mx - 3m - mx2 - mx = 0

\(\Leftrightarrow\) (2 - m)x2 - 9m = 0

Thay m = 1 ta được:

(2 - 1)x2 - 9 . 1 = 0

\(\Leftrightarrow\) x2 - 9 = 0

\(\Leftrightarrow\) (x - 3)(x + 3) = 0

\(\Leftrightarrow\) \(\left[{}\begin{matrix}x-3=0\\x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\left(KTM\right)\\x=-3\left(KTM\right)\end{matrix}\right.\)

Vậy S = \(\varnothing\)

Thay m = 2 ta được:

(2 - 2)x2 - 9 . 2 = 0

\(\Leftrightarrow\) -18 = 0

\(\Rightarrow\) Pt vô nghiệm

Vậy S = \(\varnothing\)

Chúc bn học tốt!!