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

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

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

\(-5x=3\)

\(x=\frac{-3}{5}\)

tự ghi dấu suy ra ở đằng trước nhé

b) Vì \(2x\left(5-3x\right)=2x\left(3x-5\right)-3\left(x-7\right)=3\)

nên chỉ cần giải: \(6x^2-10x-3x+21=3\)

\(\Leftrightarrow6x^2-13x+21=3\)

\(\Leftrightarrow6x^2-13x+18=0\)

\(\Rightarrow\)pt vô nghiệm

\(\left\{{}\begin{matrix}\left\{{}\begin{matrix}3x-15=45\Leftrightarrow3x=60\Leftrightarrow x=20\\35-5x=50\Leftrightarrow5x=-15\Leftrightarrow x=-3\end{matrix}\right.\\\left\{{}\begin{matrix}\left(2x-5\right)+17=6\Leftrightarrow2x+5=-11\Leftrightarrow2x=-16\Leftrightarrow x=-8\\10-2\left(4-3x\right)=-4\Leftrightarrow8-6x=14\Leftrightarrow6x=-6\Leftrightarrow x=-1\end{matrix}\right.\\\left\{{}\begin{matrix}-12+3\left(-x+7\right)=-18\Leftrightarrow-3x+21=-6\Leftrightarrow-3x=-27\Leftrightarrow x=9\\24:\left(3x-2\right)=-3\Leftrightarrow3x-2=-8\Leftrightarrow3x=-6\Leftrightarrow x=-2\end{matrix}\right.\\-45:5\left(-3-2x\right)=3\Leftrightarrow-15-10x=-15\Leftrightarrow10x=0\Leftrightarrow x=0\end{matrix}\right.\)

a) (x + 2) . (x + 3) - (x - 2) . (x + 5) = 6                

=> (x . x + 3x + 2x + 2 . 3) - (x . x + 5x - 2x - 2 . 5) = 6

=> (x² + 5x + 6) - (x² + 3x - 10) = 6                        

=> x² + 5x + 6 - x² - 3x + 10 = 6

=> 2x +16 = 6       => 2x = -10        => x = -5 

b) (3x + 2) . (2x + 9) - (x + 2) . (6x + 1) = (x + 1) - (x - 6)     

  => (3x . 2x + 3x . 9 + 2 . 2x + 2 . 9) - (x . 6x + 1x + 2 . 6x + 2 .1) = x + 1 - x + 6

=> (6x² + 31x + 18) - (6x² + 13x + 2) = 7             

=> 6x² + 31x + 18 - 6x² - 13x - 2 = 7

=> 18x + 16 = 7  => 18x = 9  => x = 0,5

c) 3 . (2x - 1) . (3x - 1) - (2x - 3) . (9x - 1) = 0

=> 3(2x . 3x - 2x -3x + 1) - (2x . 9x - 2x -3 . 9x + 3) = 0

=> 3(6x² - 5x +1) - (18x² - 29x + 3) = 0

=> (18x² -15x + 1) -(18x² - 29x +3) = 0

=> 18x² - 15x +1 -18x² + 29x - 3 = 0

=> 14x = 0  => x = 0

a)(x+2)(x+3)-(x-2)(x+5)=6

x(x+3)+2(x+3)-x(x+5)+2(x+5)=6

x²+3x+2x+6-x²-5x+2x+10=6

(x²-x²)+(3x+2x-5x+2x)+(10+6)=6

2x+16=6

2x=6-16

2x=-10

x=-10/2

x=-5. Vậy x=-5

b)3x(2x+9)+2(2x+9)-x(6x+1)-2(6x+1)=x+1-x+6

6x²+27x+4x+18-6x²-x-12x-2=7

(6x²-6x²)+(27x+4x-x-12x)+(18-2)=7

18x+16=7

18x=7-16

x=-9/18=-1/2. Vậy x=-1/2

c)[3(3x-1)](2x-1)-(2x-3)(9x-1)=0

(9x-3)(2x-1)-(2x-3)(9x-1)=0

9x(2x-1)-3(2x-1)-2x(9x-1)+3(9x-1)=0

18x²-9x-6x+3-18x²+2x+27x-3=0

(18x²-18x²)+(27x+2x-6x-9x)+(3-3)=0

14x=0

x=0/14

x=0. Vậy x=0

a) (x + 2) . (x + 3) - (x - 2) . (x + 5) = 6                    => (x . x + 3x + 2x + 2 . 3) - (x . x + 5x - 2x - 2 . 5) = 6

=> (x² + 5x + 6) - (x² + 3x - 10) = 6                          

=> x² + 5x + 6 - x² - 3x + 10 = 6

=> 2x +16 = 6  => 2x = -10    => x = -5 

b) (3x + 2) . (2x + 9) - (x + 2) . (6x + 1) = (x + 1) - (x - 6)

=> (3x . 2x + 3x . 9 + 2 . 2x + 2 . 9) - (x . 6x + 1x + 2 . 6x + 2 .1) = x + 1 - x + 6

=> (6x² + 31x + 18) - (6x² + 13x + 2) = 7

=> 6x² + 31x + 18 - 6x² - 13x - 2 = 7

=> 18x + 16 = 7  => 18x = -9  => x = -0,5

c) 3 . (2x - 1) . (3x - 1) - (2x - 3) . (9x - 1) = 0

=> 3(2x . 3x - 2x - 3x + 1) - (2x . 9x - 2x - 3. 9x + 3) = 0

=> 3(6x² - 5x + 1) - (18x² - 29x + 3) = 0

=> 18x² - 15x + 3 - 18x² + 29x -3 = 0

=> 14x = 0  => x = 0.

a) \(=15x^3-6x^2+3x\)

b) \(=x^3-8\)

c) \(=x^2+10x+25\)

 a, (x + 2) . (x - 2) - (x - 3) . (x + 1).
= x²- 4 -( x² + x -3x -3)
= x^{2 -} 4 -x² -x+ 3x + 3
= 2x-1
b.(2x + 1)² + (3x - 1)² + 2 . (2x + 1) . (3x - 1)
=( 2x +1 + 3x-1)²
=(5x)²
= 25x²

 

\(\Leftrightarrow4x^2+x-8x-2-4x^2-27x=1\)

=>-34x=3

hay x=-3/34

\(\left(x-2\right)\left(4x+1\right)-4x\left(x+7\right)=1\\ \Rightarrow4x^2-8x+x-2-4x^2-28x=1\\ \Rightarrow-35x=3\\ \Rightarrow x=\dfrac{-3}{35}\)

     (x - 2)(4x + 1) - 4x(x+7) = 1

⇔ 4x² + x - 8x - 2 - 4x² - 28x = 1

⇔ - 35x = 3

⇔ x = - 3/35

1) \(25-x^2-y^2+2xy=5^2-\left(x^2-2xy+y^2\right)=5^2-\left(x-y\right)^2\)\(=\left(5-x+y\right)\left(5+x-y\right)\)

2)  \(3x-3y-x^2+2xy-y^2\)\(=3\left(x-y\right)-\left(x^2-2xy+y^2\right)\)\(=3\left(x-y\right)-\left(x-y\right)^2\)\(=\left(x-y\right)\left(3-x+y\right)\)

1) \(25-x^2-y^2+2xy\)

\(=5^2-\left(x^2+y^2-2xy\right)\)

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

\(=\left(x-y-5\right)\left(x-y+5\right)\)

2) \(3x-3y-x^2+2xy-y^2\)

\(=3\left(x-y\right)-\left(x^2-2xy+y^2\right)\)

\(=3\left(x-y\right)-\left(x-y\right)\left(x-y\right)\)

\(=\left(3-x+y\right)\left(x-y\right)\)