K
Khách

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

14 tháng 3 2023

Bạn nên dùng công thức trực quan cho bài toán như thế này nhé.

A. x = 2

B. \(\dfrac{3}{8}=\dfrac{6}{x}\)\(\Leftrightarrow x=\dfrac{6.8}{3}=16\)

C. x = 3

D. \(x=\dfrac{4.6}{8}=3\)

E. \(x=\dfrac{7}{3}\)

G.\(\dfrac{14}{13}=\dfrac{28}{10-x}\)

<=>\(14\left(10-x\right)=364\)

<=> 10 - x = 26 

<=> x = -16 

H. \(3\left(x+2\right)=4\left(x-5\right)\)

<=> 3x + 6  = 4x - 20 

<=> -x = -26

<=> x = 26

K. \(\dfrac{x}{2}=\dfrac{8}{x}\)

<=> \(x^2=16\)

<=> \(\left[{}\begin{matrix}x=4\\x=-4\end{matrix}\right.\)

M. \(\left(x-2\right)^2=100\)

<=> \(\left[{}\begin{matrix}x-2=10\\x-2=-10\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=12\\x=-8\end{matrix}\right.\)

5 tháng 1 2023

a=2

b=16

c=3

d=3

mik chỉ biết thế này thôi(ko chắc đúng=3)

a: =>1+3x-6=7-x

=>3x-5=7-x

=>4x=12

=>x=3(nhận)

b: \(\Leftrightarrow\dfrac{x^2-x}{x+3}-\dfrac{x^2}{x-3}=\dfrac{-7x^2+3x}{\left(x-3\right)\left(x+3\right)}\)

=>\(x^3-3x^2-x^2+3x-x^3-3x^2=-7x^2+3x\)

=>\(-7x^2+3x=-7x^2+3x\)

=>0x=0(luôn đúng)

Vậy: S=R\{3;-3}

c: =>x(x+2)+(2x-1)(x+1)=0

=>2x^2+2x-x-1+x^2+2x=0

=>3x^2+3x-1=0

\(x=\dfrac{-3\pm\sqrt{21}}{6}\)

d: =>2(x-2)-x-1=3x-11

=>3x-11=2x-4-x-1=x-5

=>2x=6

=>x=3(nhận)

18 tháng 2 2023

e c.on nhiều ạ

20 tháng 12 2022

a: \(=\dfrac{x^2-x+x+1+2x}{\left(x-1\right)\left(x+1\right)}=\dfrac{\left(x+1\right)^2}{\left(x-1\right)\left(x+1\right)}=\dfrac{x+1}{x-1}\)

b: \(=\dfrac{x^2+2x-4x-2x+4}{\left(x-2\right)\left(x+2\right)}=\dfrac{x^2-4x+4}{\left(x-2\right)\left(x+2\right)}=\dfrac{x-2}{x+2}\)

c: \(=\dfrac{2x^2-3x-9-x^2+3x+x^2+6x+9}{\left(x-3\right)\left(x+3\right)}\)

\(=\dfrac{2x^2+6x}{\left(x-3\right)\left(x+3\right)}=\dfrac{2x}{x-3}\)

31 tháng 7 2021

a, ĐK: \(\left(x+1\right)\left(x^2+2x-1\right)\ge0\)

\(x^2+5x+2=4\sqrt{x^3+3x^2+x-1}\)

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

TH1: \(x\ge-1\)

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

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

\(\Leftrightarrow\left[{}\begin{matrix}x^2+2x-1=x+1\\x^2+2x-1=9x+9\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x^2+x-2=0\\x^2-7x-10=0\end{matrix}\right.\)

\(\Leftrightarrow...\)

TH2: \(x< -1\)

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

\(\Leftrightarrow...\)

Bài này dài nên ... cho nhanh nha, đoạn sau dễ rồi

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 \(x^2+10x+16=a\)

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

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

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

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

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

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

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

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

7 tháng 3 2021

a) \(\dfrac{x}{5}=\dfrac{2}{5}\)

\(\Rightarrow5x=10\)

\(\Leftrightarrow x=2\)

Vậy x = 2

b) ĐKXĐ: \(x\ne0\)

 \(\dfrac{3}{-8}=\dfrac{6}{-x}\)

\(\Rightarrow-3x=-48\)

\(\Leftrightarrow x=16\)

Vậy x = 16

c) \(\dfrac{1}{9}=\dfrac{-2x}{10}\)

\(\Rightarrow-18x=10\)

\(\Leftrightarrow x=-\dfrac{5}{9}\)

Vậy \(x=-\dfrac{5}{9}\)

d) ĐKXĐ: \(x\ne0\)

 \(\dfrac{3}{x}-5=\dfrac{-9}{x}+2\)

\(\Leftrightarrow\dfrac{3-5x}{x}=\dfrac{-9+2x}{x}\)

\(\Rightarrow3-5x=-9+2x\)

\(\Leftrightarrow7x=12\)

\(\Leftrightarrow x=\dfrac{12}{7}\)

Vậy \(x=\dfrac{12}{7}\)

e) ĐKXĐ: \(x\ne0\)

 \(\dfrac{x}{-2}=\dfrac{-8}{x}\)

\(\Rightarrow x^2=16\)

\(\Leftrightarrow x=\pm4\)

Vậy \(x=\pm4\)

 

a) Ta có: \(\dfrac{x}{5}=\dfrac{2}{5}\)

\(\Leftrightarrow x=\dfrac{2\cdot5}{5}=2\)

Vậy: x=2

b) Ta có: \(\dfrac{3}{-8}=\dfrac{6}{-x}\)

\(\Leftrightarrow-x=\dfrac{6\cdot\left(-8\right)}{3}=-16\)

hay x=16

Vậy: x=16

27 tháng 3 2020
https://i.imgur.com/cGrmxY5.jpg

a) Ta có: \(\left(x-3\right)=\left(3-x\right)^2\)

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

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

\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=4\end{matrix}\right.\)

b) Ta có: \(x^3+\dfrac{3}{2}x^2+\dfrac{3}{4}x+\dfrac{1}{8}=\dfrac{1}{64}\)

\(\Leftrightarrow x^3+3\cdot x^2\cdot\dfrac{1}{2}+3\cdot x\cdot\dfrac{1}{4}+\left(\dfrac{1}{2}\right)^3=\dfrac{1}{64}\)

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

\(\Leftrightarrow x+\dfrac{1}{2}=\dfrac{1}{4}\)

hay \(x=-\dfrac{1}{4}\)

c) Ta có: \(8x^3-50x=0\)

\(\Leftrightarrow2x\left(4x^2-25\right)=0\)

\(\Leftrightarrow x\left(2x-5\right)\left(2x+5\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{5}{2}\\x=-\dfrac{5}{2}\end{matrix}\right.\)

e) Ta có: \(x\left(x+3\right)-x^2-3x=0\)

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

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

f) Ta có: \(x^3+27+\left(x+3\right)\left(x-9\right)=0\)

\(\Leftrightarrow\left(x+3\right)\left(x^2-3x+9\right)+\left(x+3\right)\left(x-9\right)=0\)

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

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

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\\x=-3\end{matrix}\right.\)