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a. 3(2x - 1)(3x - 1) - (2x - 3)(9x - 1) = 0

<=> 3(6x2-5x+1)-(18x2-29x+3)=0

<=> 14x=0

<=> x=0

b. (x - 3)(x - 5) + 3 (x - 1) = (x - 1)(x - 3)

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

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

<=> -x+9=0

<=> x=9

c. (x - 1)(x - 2) - (x + 2)(x + 1) = 8

<=> x2-3x+2-(x2+3x+2)=8

<=> -6x=8

<=> \(x=\frac{-4}{3}\)

11 tháng 11 2020

a)(x+2).(x+3)-(x-2).(x+5)=10

  ( x^2 +3x+2x+6)-(x^2 +5x-2x-10)=10

 x^2 +3x+2x+6-x^2 -5x+2x+10-10=0

 2x+6=0

2x=-6

x=-3

14 tháng 10 2018

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

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

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

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

2) \(3x\left(x-3\right)-\left(2x-6\right)=0\)

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

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

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

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

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

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

\(\left(4-x\right)\left(5x-6\right)=0\)

\(\Rightarrow\orbr{\begin{cases}4-x=0\\5x-6=0\end{cases}\Rightarrow\orbr{\begin{cases}x=4\\x=\frac{6}{5}\end{cases}}}\)

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

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

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

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

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

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

5) \(6-4x-\left(2x-3\right)\left(x-3\right)=0\)

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

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

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

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

6) \(2x^2-5x-7=0\)

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

\(2x\left(x+1\right)-7\left(x+1\right)=0\)

\(\left(x+1\right)\left(2x-7\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x+1=0\\2x-7=0\end{cases}\Rightarrow\orbr{\begin{cases}x=-1\\x=\frac{7}{2}\end{cases}}}\)

7) \(x^2-x-12=0\)

\(x^2+3x-4x-12=0\)

\(x\left(x+3\right)-4\left(x+3\right)\)

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

\(\Rightarrow\orbr{\begin{cases}x+3=0\\x-4=0\end{cases}\Rightarrow\orbr{\begin{cases}x=-3\\x=4\end{cases}}}\)

8) \(3x^2+14x-5=0\)

\(3x^2+15x-x-5=0\)

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

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

\(\Rightarrow\orbr{\begin{cases}x+5=0\\3x-1=0\end{cases}\Rightarrow\orbr{\begin{cases}x=-5\\x=\frac{1}{3}\end{cases}}}\)

2 tháng 7 2018

(x+2)(x+3)-(x-2)(x+5)=0

=> x2+5x+6-x2-3x+10=0

=>2x+16=0 

 =>2x=-16

=>x=-8

6 tháng 3 2020

đề là gì

a)\(\left(3x-2\right)\left(x+6\right)\left(x^2+5\right)=0\)

\(\Leftrightarrow\hept{\begin{cases}3x-2=0\\x+6=0\\x^2+5=0\end{cases}\Leftrightarrow\hept{\begin{cases}3x=2\\x=-6\\x^2=-5\end{cases}\Leftrightarrow}\hept{\begin{cases}x=\frac{2}{3}\\x=-6\\x\in\varnothing\end{cases}}}\)

vậy x=2/3 hoặc x=-6

6 tháng 3 2020

a, (3x-2) (x+6) (x^2 +5) = 0 

<=> 3x - 2 = 0 hoặc x + 6 = 0 hoặc x2 + 5 = 0 (loại vì x2 \(\ge\)0 => x2 + 5 > 0)

<=> x = 2/3 hoặc x = -6 

b, (2x+5)^2 = (3x-1)^2 

<=> (2x + 5)2 - (3x - 1)2 = 0

<=> (2x + 5 - 3x + 1)(2x + 5 + 3x - 1) = 0

\(\Leftrightarrow\orbr{\begin{cases}2x-3x+6=0\\2x+3x+4=0\end{cases}\Leftrightarrow\orbr{\begin{cases}-x=-6\\5x=4\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=6\\x=\frac{4}{5}\end{cases}}}\)

c, 4x2 (x-1) - x+1 = 0

<=> 4x2(x - 1) - (x - 1) = 0

<=> (x - 1)(4x2 - 1) = 0

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

vậy x - 1 = 0 hoặc 2x - 1 = 0 hoặc 2x + 1 = 0

hay x = 1 hoặc x = 1/2 hoặc x = -1/2