\(x=2\)

\(x=0,5\)

\(x=3,125\)

a. 

x = 2 ; 3

b. 

x = 0

c. 

x = 3,125

a, (3 - x) = (3 - x)² 
Suy ra 3-x = 1 hoặc 3-x = 0
--Nếu 3-x = 1
          x = 3-1
          x = 2
--Nếu 3-x = 0
          x = 3 - 0
          x = 3
Vậy x=2; x=3
b, x³ - 0,25x = 0
    x.(x² - 0,25) = 0
Suy ra x = 0   hoặc   x² - 0,25 = 0
                                 x² = 0 + 0,25
                                 x² = 0,25
                                 x² = (0,5)² 
                                 Suy ra x = 0,5
Vậy x = 0; x = 0,5
c, x2 - 10x = -25
    x.(2 - 10) = -25
    x.(-8) = -25
    x = -25 : (-8)
    x = 25/8
Vậy x = 25/8
Chúc bạn học tốt

2D

6

\(x^3+125=\left(x+5\right)\left(x^2-5x+25\right)\)

A là đa thức bậc 1

=>A=x+5

=>B=x^2-5x+25

=>Chọn A

Câu 2. M có bậc 2 + 7 = 9

Chọn D

Câu 6. x³ + 125 = x³ + 5³ = (x + 5)(x² - 5x + 25)

Chọn A

Mình cần gấp ạk

A và B

Bài 3

a) x² + 10x + 25

= x² + 2.x.5 + 5²

= (x + 5)²

b) 8x - 16 - x²

= -(x² - 8x + 16)

= -(x² - 2.x.4 + 4²)

= -(x - 4)²

c) x³ + 3x² + 3x + 1

= x³ + 3.x².1 + 3.x.1² + 1³

= (x + 1)³

d) (x + y)² - 9x²

= (x + y)² - (3x)²

= (x + y - 3x)(x + y + 3x)

= (y - 2x)(4x + y)

e) (x + 5)² - (2x - 1)²

= (x + 5 - 2x + 1)(x + 5 + 2x - 1)

= (6 - x)(3x + 4)

Bài 4

a) x² - 9 = 0

x² = 9

x = 3 hoặc x = -3

b) (x - 4)² - 36 = 0

(x - 4 - 6)(x - 4 + 6) = 0

(x - 10)(x + 2) = 0

x - 10 = 0 hoặc x + 2 = 0

*) x - 10 = 0

x = 10

*) x + 2 = 0

x = -2

Vậy x = -2; x = 10

c) x² - 10x = -25

x² - 10x + 25 = 0

(x - 5)² = 0

x - 5 = 0

x = 5

d) x² + 5x + 6 = 0

x² + 2x + 3x + 6 = 0

(x² + 2x) + (3x + 6) = 0

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

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

x + 2 = 0 hoặc x + 3 = 0

*) x + 2 = 0

x = -2

*) x + 3 = 0

x = -3

Vậy x = -3; x = -2

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

b) \(x^2-10x+25-3\left(x-5\right)=\left(x-5\right)^2-3\left(x-5\right)=\left(x-5\right)\left(x-5-3\right)=\left(x-5\right)\left(x-8\right)\)

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

a)\(\left(2x+3\right)^2-2\left(2x+3\right)\left(2x-5\right)+\left(2x-5\right)^2=x^2+6x+64\)

\(\Rightarrow\left[\left(2x+3\right)-\left(2x-5\right)\right]^2=x^2+6x+64\)

\(\Rightarrow\left(2x+3-2x+5\right)^2=x^2+6x+64\)

\(\Rightarrow8^2=x^2+6x+64\)

\(\Rightarrow64=x^2+6x+64\)

\(\Rightarrow x^2+6x=0\)

\(\Rightarrow x\left(x+6\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=0\\x+6=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=0\\x=-6\end{matrix}\right.\)

b) \(\left(x^4+2x^3+10x-25\right):\left(x^2+5\right)=3\)

\(\Rightarrow\left(x^4+5x^2-5x^2-25+2x^3+10x\right):\left(x^2+5\right)=3\)

\(\Rightarrow\left[x^2\left(x^2+5\right)-5\left(x^2+5\right)+2x\left(x^2+5\right)\right]:\left(x^2+5\right)=3\)

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

\(\Rightarrow x^2+2x-5=3\)

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

\(\Rightarrow x^2+2x-8=0\)

\(\Rightarrow x^2+4x-2x-8=0\)

\(\Rightarrow x\left(x+4\right)-2\left(x+4\right)=0\)

\(\Rightarrow\left(x+4\right)\left(x-2\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x+4=0\\x-2=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=-4\\x=2\end{matrix}\right.\)

\(1,\Leftrightarrow x^2-10x+25=0\Leftrightarrow\left(x-5\right)^2=0\Leftrightarrow x=5\left(B\right)\\ 2,Giống.1\\ 3,=5x^2\left(B\right)\\ 4,x^3=x\Leftrightarrow x^3-x=0\\ \Leftrightarrow x\left(x^2-1\right)=0\\ \Leftrightarrow x\left(x-1\right)\left(x+1\right)=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=1\\x=-1\end{matrix}\right.\\ \Leftrightarrow A\)

a. 5x + 3(x² - x - 1)

= 5x + 3x² - 3x - 3

= 3x² + 5x - 3x - 3

= 3x² + 2x - 3

b. (5 - x)(5 + x) - (2x - 1)²

25 - x² - (4x² - 4x + 1)

= 25 - x² - 4x² + 4x - 1

= 25 - 1 - x² - 4x² + 4x 

= 24 - 5x² + 4x

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

b) \(\left(5-x\right)\left(5+x\right)-\left(2x-1\right)^2=25-x^2-4x^2+4x-1=-5x^2+4x+24\)

\(a) 5x+3(x^2-x-1)=5x+3x^2-3x-3\)

\(=3x^2-2x-3\)

\(b)(5-x)(5+x)-(2x-1)^2=25-x^2-4x^2+4x-1\)

\(=-5x^2+4x-24\)

a) (a - 2b)x(a + 2b)
b) x²-(y-3)²
 => (x-y+3)(x+y-3)
c) (2a + b - a)(2a + b + a)
=> (a+b)(3a+b)
d) (4(x - 1))² - (5(x + y))²
⇔ (4x - 4 - 5x - 5y)(4x - 4 + 5x + 5y)
⇔ -(x + 5y + 4)(9x + 5y + -4)
e) (x + 5)²
f) (5x - 2y)²
h) (x - 5)(x² + 5x + 25)

k) (x + 5)³