K
Khách

Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.

17 tháng 3 2020

\(4\left(x-2\right)^2=25\left(1-2x\right)^2\)

\(\Leftrightarrow4x^2-16x+16=25-100x+100x^2\)

\(\Leftrightarrow4x^2-16x+16-25+100x-100x^2=0\)

\(\Leftrightarrow-96x^2+84x-9=0\)

\(\Leftrightarrow-3\left(32x^2-4x-24x+3\right)=0\)

\(\Leftrightarrow-3\left[4x\left(8x-1\right)-3\left(8x-1\right)\right]=0\)

\(\Leftrightarrow\left(8x-1\right)\left(4x-3\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}8x-1=0\\4x-3=0\end{cases}\Leftrightarrow\orbr{\begin{cases}8x=1\\4x=3\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=\frac{1}{8}\\x=\frac{3}{4}\end{cases}}}\)

Vậy ...

Vậy thôi !

17 tháng 3 2020

4(x - 2)2 = 25(1 - 2x)2

<=> (2x - 4)2 - (5 - 10x)2 = 0

<=> (2x - 4 - 5 + 10x)(2x - 4 + 5 - 10x) = 0

<=> (12x - 9)(-8x + 1) = 0

<=> \(\orbr{\begin{cases}12x-9=0\\-8x+1=0\end{cases}}\)

<=> \(\orbr{\begin{cases}x=\frac{3}{4}\\x=\frac{1}{8}\end{cases}}\)

Vậy S = {3/4; 1/8}

18 tháng 4 2015

tìm x biết:

(3x-1) [- 1/2x+5]=0

1/4+1/3:(2x-1)=-5

[2x+3/5]2 - 9/25=0

-5(x+1/5)-1/2(x-2/3)=3/2x - 5 /6

[x+1/2]x [2/3-2x]=0

17/2-|2x-3/4|=-7/4

2/3x-1/2x =5/12

(x+1/5)2+17/25=26/25

[x.44/7+3/7].11/5-3/7=-2

3[3x-1/2]+1/9=0

Toán lớp 6Tìm x

 Trả lời  Câu hỏi tương tự

Chưa có ai trả lời câu hỏi này,bạn hãy là người đâu tiên giúp nguyenvanhoang giải bài toán này !

24 tháng 5 2017

3(3x-1/2)^3+1/9=0

8 tháng 9 2023

\(e,4\left(x-3\right)^2-\left(2x-1\right)\left(2x+1\right)=10\)

\(\Leftrightarrow4\left(x^2-6x+9\right)-\left(4x^2-1\right)=10\)

\(\Leftrightarrow4x^2-24x+36-4x^2+1=10\)

\(\Leftrightarrow-24x+37=10\)

\(\Leftrightarrow-24x=-27\)

\(\Leftrightarrow x=\dfrac{9}{8}\)

\(f,25\left(x+3\right)^2+ \left(1-5x\right)\left(1+5x\right)=8\)

\(\Leftrightarrow25\left(x^2+6x+9\right)+\left(1-25x^2\right)=8\)

\(\Leftrightarrow25x^2+150x+225+1-25x^2=8\)

\(\Leftrightarrow150x+226=8\)

\(\Leftrightarrow150x=-218\)

\(\Leftrightarrow x=-\dfrac{109}{75}\)

\(g,9\left(x+1\right)^2-\left(3x-2\right)\left(3x+2\right)=10\)

\(\Leftrightarrow9\left(x^2+2x+1\right)-\left(9x^2-4\right)=10\)

\(\Leftrightarrow9x^2+18x+9-9x^2+4=10\)

\(\Leftrightarrow18x+13=10\)

\(\Leftrightarrow18x=-3\)

\(\Leftrightarrow x=-\dfrac{1}{6}\)

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

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

\(\Leftrightarrow-4x^2+8x-4+4x^2-1=-3\)

\(\Leftrightarrow8x-5=-3\)

\(\Leftrightarrow8x=2\)

\(\Leftrightarrow x=\dfrac{1}{4}\)

#\(Toru\)

17 tháng 12 2020

a) x(2x - 1) - (x - 2)(2x + 3) = 5

2x2 - x - 2x2 - 3x + 4x + 6 = 5

0x = -1 (vô lý)

Vậy không tìm được x

b) (x - 3)2 - 25 = 0

(x - 3)2 - 52 = 0

(x - 3 - 5)(x - 3 + 5) = 0

(x - 8)(x + 2) = 0

\(\Rightarrow\) x - 8 = 0 hoặc x + 2 = 0

*) x - 8 = 0

x = 0 + 8

x = 8

*) x + 2 = 0

x = 0 - 2

x = -2

Vậy x = 8; x = -2

c) (x - 1)(2 - x) + (x + 3)2 = 4 - 2x

2x - x2 - 2 + x + x2 + 6x + 9 = 4 - 2x

9x + 7 = 4 - 2x

9x + 2x = 4 - 7

11x = -3

x = \(\dfrac{-3}{11}\)

Vậy x = \(\dfrac{-3}{11}\)

29 tháng 4 2019

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

\(\Leftrightarrow\orbr{\begin{cases}x+\frac{1}{2}=0\\\frac{2}{3}-2x=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=\frac{-1}{2}\\x=\frac{1}{3}\end{cases}}\)

Vậy \(x\in\left\{\frac{-1}{2};\frac{1}{3}\right\}\)

29 tháng 4 2019

f. \(\frac{2}{3}x-\frac{1}{2}x=\frac{5}{12}\)

\(\Leftrightarrow x\left(\frac{2}{3}-\frac{1}{2}\right)=\frac{5}{12}\)

\(\Leftrightarrow x\left(\frac{4}{6}-\frac{3}{6}\right)=\frac{5}{12}\)

\(\Leftrightarrow\frac{1}{6}x=\frac{5}{12}\)

\(\Leftrightarrow x=\frac{5}{12}\div\frac{1}{6}\)

\(\Leftrightarrow x=\frac{30}{12}=\frac{5}{2}\)

21 tháng 8 2021

a) \(\left(x+3\right)^2-\left(x-2\right)^3=\left(x+5\right)\left(x^2-5x+25\right)-108\)

\(\Leftrightarrow x^2+6x+9-x^2+4x-4=x^3-5x^2+25x+5x^2-25x+125-108\)

\(\Leftrightarrow x^3-10x+12=0\Leftrightarrow\left(x-2\right)\left(x^2+2x+6\right)=0\)

\(\Leftrightarrow x=2\)( do \(x^2+2x+6=\left(x+1\right)^2+4\ge4>0\))

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

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

\(\Leftrightarrow2x^2-2x+5x-5+x^2+2x-3-4-3x^2-10x+x+3=0\)

\(\Leftrightarrow-4x=9\)

hay \(x=-\dfrac{9}{4}\)

10) Ta có: \(\dfrac{x-1}{x+3}-\dfrac{x}{x-3}=\dfrac{7x-3}{9-x^2}\)

\(\Leftrightarrow\dfrac{\left(x-1\right)\left(x-3\right)}{\left(x+3\right)\left(x-3\right)}-\dfrac{x\left(x+3\right)}{\left(x-3\right)\left(x+3\right)}=\dfrac{3-7x}{\left(x-3\right)\left(x+3\right)}\)
Suy ra: \(x^2-4x+3-x^2-3x-3+7x=0\)

\(\Leftrightarrow0x=0\)(luôn đúng)

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

11) Ta có: \(\dfrac{5+9x}{x^2-16}=\dfrac{2x-1}{x+4}+\dfrac{3x-1}{x-4}\)

\(\Leftrightarrow\dfrac{\left(2x-1\right)\left(x-4\right)}{\left(x-4\right)\left(x+4\right)}+\dfrac{\left(3x-1\right)\left(x+4\right)}{\left(x-4\right)\left(x+4\right)}=\dfrac{9x+5}{\left(x-4\right)\left(x+5\right)}\)

Suy ra: \(2x^2-9x+4+3x^2+12x-x-4-9x-5=0\)

\(\Leftrightarrow5x^2-7x=0\)

\(\Leftrightarrow x\left(5x-7\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{7}{5}\end{matrix}\right.\)

12) Ta có: \(\dfrac{2x}{2x-1}+\dfrac{x}{2x+1}=1+\dfrac{4}{\left(2x-1\right)\left(2x+1\right)}\)

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

Suy ra: \(4x^2+2x+2x^2-x-4x^2-3=0\)

\(\Leftrightarrow2x^2+x-3=0\)

\(\Leftrightarrow2x^2+3x-2x-3=0\)

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

\(\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{3}{2}\\x=1\end{matrix}\right.\)

26 tháng 10 2021

1) ĐKXĐ: \(x\ge\dfrac{5}{2}\)

\(\sqrt{x^2}=2x-5\\ \Rightarrow\left|x\right|=2x-5\\ \Rightarrow\left[{}\begin{matrix}x=2x-5\\x=5-2x\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=5\left(tm\right)\\x=\dfrac{5}{3}\left(ktm\right)\end{matrix}\right.\)

2) ĐKXĐ: \(x\ge3\)

\(\sqrt{25x^2-10x+1}=2x-6\\ \Rightarrow\left|5x-1\right|=2x-6\\ \Rightarrow\left[{}\begin{matrix}5x-1=2x-6\\5x-1=6-2x\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=-\dfrac{5}{3}\left(ktm\right)\\x=1\left(tm\right)\end{matrix}\right.\)

3) ĐKXĐ: \(x\ge\dfrac{5}{2}\)

\(\sqrt{25-10x+x^2}=2x-5\\ \Rightarrow\left|x-5\right|=2x-5\\ \Rightarrow\left[{}\begin{matrix}x-5=2x-5\\x-5=5-2x\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=0\left(ktm\right)\\x=\dfrac{10}{3}\left(tm\right)\end{matrix}\right.\)

4) ĐKXĐ: \(x\ge\dfrac{1}{2}\)

\(\sqrt{1-2x+x^2}=2x-1\\ \Rightarrow\left|x-1\right|=2x-1\\ \Rightarrow\left[{}\begin{matrix}x-1=2x-1\\x-1=1-2x\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=0\left(ktm\right)\\x=\dfrac{2}{3}\left(tm\right)\end{matrix}\right.\)

 

13 tháng 10 2021

3: \(\left(x+5\right)\left(x^2-5x+25\right)-x\left(x-4\right)^2+16x\)

\(=x^3+125-x^3+8x^2-16x+16x\)

\(=8x^2+125\)