\(a.\left(2x-1\right)^2-\left(4x-3\right)\left(x+5\right)=0\)  \(\Leftrightarrow4x^2-4x+1-\left(4x^2+17x-15\right)=0\)

\(\Leftrightarrow-21x+16=0\Leftrightarrow x=\dfrac{16}{21}\) . Vậy ... 

b.\(x\left(x-1\right)=3\left(x-1\right)\Leftrightarrow\left(x-3\right)\left(x-1\right)=0\)  \(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=1\end{matrix}\right.\) . Vậy ...

c.\(\left(x-1\right)\left(3x-7\right)=\left(x-1\right)\left(x+3\right)\Leftrightarrow\left(x-1\right)\left(3x-7-x-3\right)=0\)

\(\Leftrightarrow2\left(x-1\right)\left(x-5\right)=0\Leftrightarrow\left[{}\begin{matrix}x=1\\x=5\end{matrix}\right.\) . Vậy ... 

d.\(\left(x-3\right)^2+2x-6=0\Leftrightarrow\left(x-3\right)\left(x-3+2\right)=0\) \(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=1\end{matrix}\right.\) . Vậy ... 

a) (x-2)² -(x-3)(x-3)=6

=>x² -4x+4-x²+3=6

=>7-4x=6

=>4x=1 =>x=\(\frac{1}{4}\)

b)4(x-3)² -(2x-1)(2x+1)=10

=>4(x²-6x+9)-4x²+1=10

=>4x²-24x+36-4x²+1=10

=>37-24x=10 =>24x=27 =>x=\(\frac{9}{8}\)

c)x²-16-3(x+4)=0

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

=>(x-7)(x+4)=0

=>\(\orbr{\begin{cases}x-7=0\\x+4=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=7\\x=-4\end{cases}}}\)

=>x\(\in\left\{-4;7\right\}\)

d)(x-4)²-(x-2)(x+2)=6

=>x²-8x+16-x²+4=6

=>20-8x=6

=>8x=14 =>x=\(\frac{4}{7}\)

e) 9(x+1)²-(3x-2)(3x+2)=10

=>9(x² +2x+1)-9x²+4=10

=>9x²+18x+9-9x²+4=10

=>18x+13=10

=>18x=-3

=>x=\(\frac{-1}{6}\)

mình chỉ làm bài 1 nha

nhớ chon mk đúng nha

Cảm ơn bạn nha . Ai giúp mình làm bài 2 với TT

2,

B=-2x²+6x-11=-2(x²-3x+\(\frac{4}{9}\)) - \(\frac{91}{9}\)

=-2(x+\(\frac{2}{3}\))²-\(\frac{91}{9}\)

vì (x+\(\frac{2}{3}\))² \(\ge\)0  với mọi x\(\in\)R

=> -2(x+\(\frac{2}{3}\))²\(\le\)0 với mọi x\(\in\)R

=> -2(x+\(\frac{2}{3}\))² -\(\frac{91}{9}\)\(\le-\frac{91}{9}\)với mọi x\(\in\)R

dấu bằng xảy ra khi -2(x+\(\frac{2}{3}\))² =0 hay x+\(\frac{2}{3}\)=0 =>x=-\(\frac{2}{3}\)

vậy GTLN của B=-\(\frac{91}{9}\)khi x=-\(\frac{2}{3}\)

2x + 5 ⋮ x + 2 <=> 2( x + 2 ) + 1 ⋮ x + 2

Vì 2( x + 2 ) ⋮ x + 2 Để 2( x + 2 ) + 1 ⋮ x + 2 <=> 1 ⋮ x + 2 

=> x + 2 là ước của 1 => Ư(1) = { -1 ; 1 }

Ta có : x + 2 = 1 => x = -1

           x + 2 = - 1 => x = -3

Vậy x = { -1;'-3 }

a)   ( 2x + 3)^2 = 121

        2x + 3^2   = 121

         2x + 9      = 121

                 2x    = 121 - 9

                  2x   =   112

                     x  =  112 : 2

                      x = 56

Mấy câu sau tự làm nhé bạn 

a) (2x + 3)² = 121

    (2x + 3)² = 11²

^=>   2x + 3 = 11

     2x       = 11 - 3

     2x       = 8

       x      = 8 : 2

       x       = 4

b) (75 - 3x)³ = 27

    ( 75 - 3x)³ = 3³

=> 75 - 3x     = 3

            3x     = 75- 3

            3x     =  72

              x     = 72 : 3

              x      = 24

a,11²=121

=>(2x+3)=11

=>2x=8=>x=4

b,3³=27

=>75-3x=3

=>3x=72

=>x=24

c,16¹³=(2⁴)¹³

=2^4.13=2⁵²

=>2^x=2⁶⁰:2⁵²

=>2^x=2⁸=>x=8

CHUC BN HOC TOT

1 Life in the country is not as good as life in the city

2 These room are cleaned every evening

3 Would you mind decorating the christmas tree

4 It's the first time I have talked to the headmaster

V

1 have ever met

2 worked

3 reading

4 are looking - seeing

5 was

VI

1A

2A

3D

4D

5B

IV/

1. is not as good as life in the city

2. are cleaned every evening

3. decorating the Christmas tree?

4. the first time I have (ever) talked to the headmaster

V/

1. have ever met

2. worked

3. reading

4. are looking - seeing

5. was

VI/

1a 2a 3d 4d 5b

đáp án án là: x^2+2x+2