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12 tháng 6 2018

Đơn giản như đang dỡn :V

a )

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

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

\(\Leftrightarrow\left[{}\begin{matrix}x+3=0\\5-2x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=\dfrac{5}{2}\end{matrix}\right.\)

Vậy..........................

b )

\(4x\left(x-2004\right)-x+2004=0\)

\(\Leftrightarrow4x\left(x-2004\right)-\left(x-2004\right)=0\)

\(\Leftrightarrow\left(x-2004\right)\left(4x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-2004=0\\4x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2004\\x=\dfrac{1}{4}\end{matrix}\right.\)

Vậy.....................

c )

\(\left(x+1\right)^2=x+1\)

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

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

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

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-1\end{matrix}\right.\)

Vậy.............

12 tháng 6 2018

Tìm x:

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

<=>(x+3)(5-2x)=0<=>\(\left\{{}\begin{matrix}x=-3\\x=\dfrac{5}{2}\end{matrix}\right.\)

(x+1)^2=x+1

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

<=>x(x+1)=0

<=>\(\left\{{}\begin{matrix}x=0\\x=-1\end{matrix}\right.\)

(bạn ơi , mk ko biết làm câu : 4x(x-2004)-x+2004=0 đâu . Tại vì mk mới học lớp 6 nâng cao nên ko biết làm bài lớp 7 đâu .)

19 tháng 9 2016

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

\(\Leftrightarrow\left(x+3\right)\left(5-2x\right)=0\) \(\Leftrightarrow\left[\begin{array}{nghiempt}x=-3\\x=\frac{5}{2}\end{array}\right.\)

b/ \(4x\left(x-2004\right)-x+2004=0\)

\(\Leftrightarrow4x\left(x-2004\right)-\left(x-2004\right)=0\)

\(\Leftrightarrow\left(x-2007\right)\left(4x-1\right)=0\) \(\Leftrightarrow\left[\begin{array}{nghiempt}x=2007\\x=\frac{1}{4}\end{array}\right.\)

c/ \(\left(x+1\right)^2=x+1\Leftrightarrow\left(x+1\right)\left(x+1-1\right)=0\Leftrightarrow x\left(x+1\right)=0\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}x=0\\x=-1\end{array}\right.\)

19 tháng 9 2016

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

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

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

\(\Rightarrow\left[\begin{array}{nghiempt}5-2x=0\\x+3=0\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}x=\frac{5}{2}\\x=-3\end{array}\right.\)

 

24 tháng 9 2016

Tìm x

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

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

\(\Leftrightarrow\left[\begin{array}{nghiempt}x=-3\\x=\frac{5}{2}\end{array}\right.\)

b) 4x(x-2004)-x+2004

\(\Leftrightarrow4x\left(x-2004\right)-\left(x-2004\right)=0\) 

\(\Leftrightarrow\left(x-2007\right)\left(4x-1\right)=0\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}x=2007\\x=\frac{1}{4}\end{array}\right.\)

c) (x+1)2=x+1

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

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

\(\Leftrightarrow\left[\begin{array}{nghiempt}x=0\\x=-1\end{array}\right.\)

24 tháng 9 2016

c) \(\left(x+1\right)^2=x+1\)

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

\(\Rightarrow x+1.\left(x+1-1\right)=0\)

\(\Rightarrow\left(x+1\right).x=0\)

\(\Rightarrow x+1=0\) hoặc \(x=0\)

+) \(x+1=0\Rightarrow x=-1\)

Vậy x = 0 hoặc x = -1

28 tháng 6 2017

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

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

c.\(\left(x+1\right)^2=x+1\Leftrightarrow\left(x+1\right)x=0\)\(\Leftrightarrow\orbr{\begin{cases}x=0\\x+1=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=0\\x=-1\end{cases}}}\)

28 tháng 6 2017

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

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

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

b)\(4x\left(x+2004\right)-x+2004=0\)

   \(4x^2+8016x-x+2004 =0\)

   \(4x^2+8015x+2004=0\)

             Xem lại đề

23 tháng 9 2017

Bài 1:

a.\(y.\left(x-z\right)+7\left(z-x\right)\)

\(=y\left(x-z\right)-7\left(x-z\right)\)

\(=\left(y-7\right)\left(x-z\right)\)

b,\(27x^2\left(y-1\right)-9x^3\left(1-y\right)\)

\(=27x^2\left(y-1\right)+9x^3\left(y-1\right)\)

\(=\left(27x^2+9x^3\right)\left(y-1\right)\)

Bài 2

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

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

\(\Leftrightarrow\left[{}\begin{matrix}5-2x=0\\x+3=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=2,5\\x=-3\end{matrix}\right.\)

b.\(4x\left(x-2004\right)-x+2004=0\)

\(4x\left(x-2004\right)-\left(x-2004\right)=0\)

\(\left(4x-1\right)\left(x-2004\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}4x-1=0\\x-2004=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0,25\\x=2004\end{matrix}\right.\)

c.\(\left(x+1\right)^2=x+1\)

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

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

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

\(\Leftrightarrow\left[{}\begin{matrix}x+1=0\\x+1-1=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=0\end{matrix}\right.\)

23 tháng 9 2017

bài 1

a) y(x-z)+7(z-x)= y(x-z)-7(x-z)= (x-z)(y-7)

b) 27x2.(y-1)-9x3.(1-y)= 27x2.(y-1)+9x3.(y-1)= (y-1)(27x2-9x3)

bài 2

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

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

\(\Leftrightarrow\)x+3=0 hoặc 5+2x=0

=>x=-3 hoặc x=\(\dfrac{-5}{2}\)

b)=4x(x-2014)-(x-2014)=0

= (x-2014)(4x-1)=0

\(\Leftrightarrow\)x-2014=0 hoặc 4x-1=0

=>x=2014 hoặc x= \(\dfrac{1}{4}\)

câu c) thấy kì kì, k biết làmhaha

18 tháng 8 2018

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

\(\Leftrightarrow5\left(x+3\right)-2x\left(3+x\right)=0\)

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

\(\Leftrightarrow\left[{}\begin{matrix}5-2x=0\\x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=5\\x=-3\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=-3\end{matrix}\right.\)

Vậy ...

b ) \(\left(x-2004\right)=8016x-4x^2\)

\(\Leftrightarrow x-2004=-4x\left(x-2004\right)\)

\(\Leftrightarrow x-2004+4x\left(x-2004\right)=0\)

\(\Leftrightarrow\left(x-2004\right)\left(4x+1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-2004=0\\4x+1=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=2004\\4x=-1\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=2004\\x=-\dfrac{1}{4}\end{matrix}\right.\)

Vậy ...

c ) \(\left(x+1\right)^2=x+1\)

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

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

\(\Leftrightarrow\left[{}\begin{matrix}x+1=0\\x+1-1=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=0\end{matrix}\right.\)

Vậy ...

18 tháng 8 2018

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

\(\Rightarrow5\left(x+3\right)-2x\left(3+x\right)=0\)

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

\(\Rightarrow\left[{}\begin{matrix}x+3=0\\5-2x=0\end{matrix}\right.\)

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

b) \(\left(x-2004\right)=8016x-4x^2\)

\(\Rightarrow\left(x-2004\right)=4x\left(2004-x\right)\)

\(\Rightarrow\left(x-2004\right)-4x\left(2004-x\right)=0\)

\(\Rightarrow\left(x-2004\right)+4x\left(x-2004\right)=0\)

\(\Rightarrow\left(x-2004\right)\left(1+4x\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x-2004=0\\1+4x=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=2004\\x=-\dfrac{1}{4}\end{matrix}\right.\)

c) \(\left(x+1\right)^2=x+1\)

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

\(\Rightarrow\left(x+1\right)\left(x+1-1\right)=0\)

\(\Rightarrow\left(x+1\right)x=0\)

\(\Rightarrow\left[{}\begin{matrix}x+1=0\\x=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=-1\\x=0\end{matrix}\right.\)

Câu 2: 

a: Ta có: \(\left|x+\dfrac{19}{5}\right|+\left|y+\dfrac{1890}{1975}\right|+\left|z-2004\right|=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}x+\dfrac{19}{5}=0\\y+\dfrac{1890}{1975}=0\\z-2004=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-\dfrac{19}{5}\\y=-\dfrac{378}{395}\\z=2004\end{matrix}\right.\)

b: \(\left|x-\dfrac{1}{2}\right|+\left|y+\dfrac{3}{2}\right|+\left|x-y-z-\dfrac{1}{2}\right|=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}x-\dfrac{1}{2}=0\\y+\dfrac{3}{2}=0\\x-y-z-\dfrac{1}{2}=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{1}{2}\\y=-\dfrac{3}{2}\\z=\dfrac{3}{2}\end{matrix}\right.\)

26 tháng 11 2016

Câu hỏi của Marilyna - Toán lớp 7 | Học trực tuyến