a/ \(x\left(x+7\right)=0\) \(\Rightarrow\left[\begin{matrix}x=0\\x+7=0\end{matrix}\right.\) \(\Rightarrow\left[\begin{matrix}x=0\\x=-7\end{matrix}\right.\)

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

c/ \(\left|x-1\right|=3\) \(\Rightarrow\left[\begin{matrix}x-1=3\\1-x=3\end{matrix}\right.\) \(\Rightarrow\left[\begin{matrix}x=4\\x=-2\end{matrix}\right.\)

d/ \(-13\left|x\right|=-26\) \(\Rightarrow\left|x\right|=2\) \(\Rightarrow x=\pm2\)

e/ \(x.x-8=-2.\left(-13\right)-\left(-2\right)\)

\(\Rightarrow x^2=36\) \(\Rightarrow\left|x\right|=6\) \(\Rightarrow x=\pm6\)

a) x Î{0;3}.

b) xÎ{0;-9}.

c) x Î{-l; 11}.

d) x = 13.

Trả lời:

a) x(x - 3)=0

=> x = 0 hoặc x - 3 = 0

                   => x = 3

Vậy x = 0; x = 3

b) x(x + 9)=0

=> x = 0 hoặc x + 9 = 0

                    => x = -9

Vậy x = 0; x = -9

c) (x + 1) (x - 1)=0

=> x + 1 = 0 hoặc x - 1 = 0

=>     x = -1               x = 1

Vậy x = -1; x = 1

d) (x - 13) (x² + 8)=0

=> x - 13 = 0 hoặc x² + 8 = 0

=> x = 13               x² = -8 (vô lí, vì x² \(\ge\)0)

Vậy x = 13

A)(x+5)(x-4)=0

=)x+5=0 hoặc x-4=0

=)x=-5 hoặc x=4

Nếu đề là tìm x thì làm như sau :

a) (x+5).(x-4)=0

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

Vậy x\(\in\){-5;4}

Câu b, c và d tương tự

e) 4-(27-3)=x-(13-4)

x-(13-4)=-20

x-9=-20

x=-20+9

x=-11

Vậy x=-11

f) 8-(x-10)=23-(-4+12)

8-(x-10)=15

x-10=8-15

x-10=-7

x=-7+10

x=3

Vậy x=3.

Lần sau bạn nhớ ghi yêu cầu đề bài nhé!

a)\(2x+3\left(x+4\right)-14=8\)

\(2x+3x+12-14=8\)

\(2x+3x-2=8\)

\(5x-2=8\)

\(5x=8+2\)

\(5x=10\)

\(x=10:5\)

\(x=2\)

b)\(x+2x+3x=4x+16\)

\(x\left(1+2+3\right)=4x+16\)

\(6x-4x=16\)

\(2x=16\)

\(x=16:2\)

\(x=8\)

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

\(2x+2+3x+15=0\)

\(5x+17=0\)

\(5x=0-17\)

\(5x=-17\)

\(x=-17:5\)

\(x=-\frac{17}{5}\)

a. 3.(x-2)+2.(x-3)=13

x=5

b. (x+1).(2-x)-(3x+5).(x+2)=-4x²+1

x=-9/10

c.x.(5-2x)+2x.(x-1)=13

x=13/3

d. (2x+3)²-(x-1)²=0

x=-2/3

e. x².(3x-2)-8+12=0

x vô ngiệm

f x²+x=0

x=-1

g. x³-5x=0

x=0

~~~~~~~~~~~ai đi ngang qua nhớ để lại k ~~~~~~~~~~~~~ 

~~~~~~~~~~~~ Chúc bạn sớm kiếm được nhiều điểm hỏi đáp ~~~~~~~~~~~~~~~~~~~

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

\(3x-6+2x-6=13\)

\(5x=13+6+6\)

\(5x=25\)

\(x=25\)

c)  \(x\left(5-2x\right)+2x\left(x-1\right)=13\)

\(5x-2x^2+2x^2-2x=13\)

\(3x=13\)

\(x=\frac{13}{3}\)

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

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

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

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

f)  \(x^2+x=0\)

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

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

g)   \(x^3-5x=0\)

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

\(=>\orbr{\begin{cases}x^2=0\\x-5=0\end{cases}}\)

\(=>\orbr{\begin{cases}x=0\\x=5\end{cases}}\) \(\)

\(\)

a,  3 ( x + 1 ) - 2 ( 3 x - 4 ) = - 13

=> 3x + 3 - 6x + 8 = - 13

=> 6x - 3x = 3 + 8 + 13

=> 3x = 24

=> x = 8

b, 2 ( x - 3 ) - 4 ( 2 x - 1 ) = - 20

=> 2x - 6 - 8x + 4 = - 20

=> 8x - 2x = - 6 + 4 + 20

=> 6x = 18

=> x = 3

c, 2 x ( x + 3 ) = 0

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

d, ( x - 1 ) ( 5 x - x ) = 0

=> \(\orbr{\begin{cases}x-1=0\\5x-x=0\end{cases}\Rightarrow\orbr{\begin{cases}x=1\\4x=0\end{cases}\Rightarrow}\orbr{\begin{cases}x=1\\x=0\end{cases}}}\)

e, ( x + 3 ) ² ( 4 - x ) = 0

=> \(\orbr{\begin{cases}\left(x+3\right)^2=0\\4-x=0\end{cases}\Rightarrow\orbr{\begin{cases}x+3=0\\4-x=0\end{cases}\Rightarrow}\orbr{\begin{cases}x=-3\\x=4\end{cases}}}\)

a) \(3\left(x+1\right)-2\left(3x-4\right)=-13\)

\(\Leftrightarrow3x+3-6x+8=-13\)

\(\Leftrightarrow3x-6x=-13-3-8\)

\(\Leftrightarrow-3x=-24\)

\(\Leftrightarrow x=8\)

Vậy \(x=8\)

b) \(2\left(x-3\right)-4\left(2x-1\right)=-20\)

\(\Leftrightarrow2x-6-8x+4=-20\)

\(\Leftrightarrow2x-8x=-20+6-4\)

\(\Leftrightarrow-6x=-18\)

\(\Leftrightarrow x=3\)

Vậy \(x=3\)

c) \(2x\left(x+3\right)=0\)

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

Vậy \(\orbr{\begin{cases}x=0\\x=-3\end{cases}}\)

d)\(\left(x-1\right)\left(5x-x\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x-1=0\\5x-x=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=1\\4x=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=1\\x=0\end{cases}}\)

Vậy \(\orbr{\begin{cases}x=1\\x=0\end{cases}}\)

e)\(\left(x+3\right)^2\left(4-x\right)=0\)

\(\orbr{\begin{cases}\left(x+3\right)^2=0\\4-x=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x+3=0\\-x=-4\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=-3\\x=4\end{cases}}\)

Vậy \(\orbr{\begin{cases}x=-3\\x=4\end{cases}}\)

cảm ơn bạn nhé hi hi