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

<=> ( x - 1 )( x + 2 ) - ( x + 2 ) = 0

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

<=> x = ±2

( 2x - 7 )³ = 8( 7 - 2x )²

<=> ( 2x - 7 )³ - 8( 2x - 7 )² = 0

<=> ( 2x - 7 )²( 2x - 15 ) = 0

<=> x = 7/2 hoặc x = 15/2

sao ko có = máy hít vậy

a)8x²+30x+7=0

=>8x²+28x+2x+7=0

=>(8x²+2x)+(28x+7)=0

=>2x(4x+1)+7(4x+1)=0

=>(2x+7)(4x+1)=0

\(\Rightarrow\orbr{\begin{cases}x=-\frac{7}{2}\\x=-\frac{1}{4}\end{cases}}\)

b)(x²-4x)²-8(x²-4x)+15=0

=>x⁴-8x³+8x²+32x+15=0

=>(x-5)(x+1)(x²-4x-3)=0

\(\Rightarrow\hept{\begin{cases}x=5\\x=-1\\x=2-\sqrt{7};x=\sqrt{7}+2\end{cases}}\)

x^2 -2x = 24

=> x^2 - 2x - 24=0

=>x^2 -8x+6x - 24 = 0

=> ( x^2- 8x)+( 6x-24) = 0

=> x(x-8) + 6(x-8) = 0

=> (x+6)(x-8)=0

=>\(\orbr{\begin{cases}x=-6\\x=8\end{cases}}\)

\(=\frac{\left(2.5\right)^4.3^4-2^4\left(3.5\right)^2}{2^8.5^2.3^3}=\frac{2^4.3^2.5^2\left(5^2.3^2-1\right)}{2^8.5^2.3^3}=\frac{255-1}{16.3}=\frac{14}{3}\)

$ (3x-1)(2x+7)-(x+1)(6x-5)=16 $

$ 6x^2+21x-2x-7-(6x^2+x-5)=16 $

$ 25x-7-x+5=16 $

$ 24x-2=16 $

$ 24x=18 $

$ x=\frac{3}{4} $

$ (10x+9)x-(5x-1)(2x+3)=8 $

$ 10x^2+9x-(10x^2+13x-3)=8 $

$ 10x^2+9x-10x^2-13x+3=8 $

$ -4x+3=8 $

$ -4x=5 $

$ x=-\frac{5}{4} $