1. x(x + 1) - x² + 1 = 0

<=> x(x + 1) - (x² - 1) = 0

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

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

<=> x + 1 = 0\

<=> x = -1

2. 4x(x - 2) - 6 + 3x = 0

<=> 4x(x - 2) - (3x - 6) = 0

<=> 4x(x - 2) - 3(x - 2) = 0

<=> (4x - 3)(x - 2) = 0

<=> \(\left[{}\begin{matrix}4x-3=0\\x-2=0\end{matrix}\right.\)

<=> \(\left[{}\begin{matrix}x=\dfrac{3}{4}\\x=2\end{matrix}\right.\)

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

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

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

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

2) là gì vậy bạn , 17x hay là x¹⁷

x¹⁷ đó bạn nhé

a) x = 4

b) x = 5

c) x = 2

d) x = 2

e, x = 1

f, x = 0 hoặc  x = 1

a) x = 4                

b) x = 5     

c) x = 2                

d) x = 2

e) x = 1                

f) x = 0 hoặc  x = 1.

1)
\(4x^2-4x+1-4x^2-16x-16=9\)
\(-20x-15=9\)
-20x=24
x=-1,2

3)
(2x+1)²=5²
2x+1=5
2x=4
x=2
 

\(1,\Rightarrow4x^2-4x+1-4x^2-16x-16=9\\ \Rightarrow-20x=23\Rightarrow x=-\dfrac{23}{20}\\ 2,\Rightarrow9x^2-6x+1+2x+6+11-11x^2=15\\ \Rightarrow2x^2+4x-3=0\\ \Rightarrow2\left(x^2+2x+1\right)-5=0\\ \Rightarrow2\left(x+1\right)^2-5=0\\ \Rightarrow\left[\sqrt{2}\left(x+1\right)-\sqrt{5}\right]\left[\sqrt{2}\left(x+1\right)+\sqrt{5}\right]=0\\ \Rightarrow\left[{}\begin{matrix}\sqrt{2}\left(x+1\right)=\sqrt{5}\\\sqrt{2}\left(x+1\right)=-\sqrt{5}\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x+1=\sqrt{\dfrac{5}{2}}=\dfrac{\sqrt{10}}{2}\\x+1=-\sqrt{\dfrac{5}{2}}=\dfrac{-\sqrt{10}}{2}\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{\sqrt{10}-2}{2}\\x=\dfrac{-\sqrt{10}-2}{2}\end{matrix}\right.\)

\(3,\Rightarrow\left(2x+1\right)^2-25=0\Rightarrow\left(2x+1-5\right)\left(2x+1+5\right)=0\\ \Rightarrow\left[{}\begin{matrix}2x=4\\2x=-6\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=2\\x=-3\end{matrix}\right.\)

\(4,\Rightarrow x^3+3x^2+3x+1-x^3-2x^2-2x+1-x^2=15\\ \Rightarrow x+2=15\Rightarrow x=13\)

Bài 10:

a: Để A là phân số thì n+2<>0

hay n<>-2

b: Khi n=0 thì A=3/2

Khi n=2 thì A=3/(2+2)=3/4

Khi n=-7 thì A=3/(-7+2)=-3/5

Bài 9:

1)9/x = -35/105               2) 12/5 = 32/x                   3)x/2 = 32/x                            x = 9. (-35)/105              x.12/5 = x.32/x                    2x.x/2 = 2x.32/x        

        x = -3                              x.12/5=32                         xx = 2.32

                                                        x= 32:12/5                x^2 = 2.32

                                                         x = 40/3                   x^2 = 64

                                                                                         x = 8

4) x-2/4 = x-1/5

      5(x-2) = 4(x-1)
       5x - 10 = 4x - 4
        5x - 4x = 10 - 4
         x = 6   

  Bài 10:Cho biểu thức 

a, 125 x7x( 16x5)

=875x80

=70,000

b,51x43+51x69-51x18

=51x (43+69-18)

=51x94

=4794

c,15x(467+13)+75x(427+53)

=480x(15+75)

=480x90

=43200

d, (195+196+197+....+2000)x(52x364-208x91)

=(195+196+.......+2000)x0

=0

Chúc bạn học tốt

a.125x7x(16x5)=875x80=70000

b. 51x43+51x69-51x18= 51x(49+69-18)=51x94=4791

c. 15x(467+13)+75x(427+53)= 15x480+75x480=480x(15+75)= 480x90=43200

d. (195+196+197+...+2000)x(52x364-208x91)=(195+196+...+2000)x0=0 

2/

a,x=0 or x=-3

b,x=2 or x=5

c,x=1

Lời giải:

1. $(x+2)-2=0$

$x+2=2$

$x=0$

2.

$(x+3)+1=7$

$x+3=7-1=6$

$x=6-3=3$

3.

$(3x-4)+4=12$

$3x-4+4=12$

$3x=12$

$x=12:3=4$

4.

$(5x+4)-1=13$

$5x+4=13+1=14$

$5x=14-4=10$

$x=10:5=2$

5.

$(4x-8)-3=5$

$4x-8=5+3=8$

$4x=8+8=16$

$x=16:4=4$

6.

$3+(x-5)=7$

$x-5=7-3=4$

$x=4+5=9$

7.

$8-(2x-4)=2$

$2x-4=8-2=6$

$2x=6+4=10$

$x=10:2=5$

8.

$7+(5x+2)=14$

$5x+2=14-7=7$

$5x=7-2=5$

$x=5:5=1$

9.

$5-(3x-11)=1$

$3x-11=5-1=4$

$3x=11+4=15$

$x=15:3=5$

10.

$16-(8x+2)=6$

$8x+2=16-6=10$

$8x=10-2=8$

$x=8:8=1$