1. 5( x^2 - 2x -1 ) + 2( 3x - 2) = 5( x + 10) ^2
<=> 5x^2 - 10x - 5 + 6x - 4 = 5 ( x^2 + 20x + 100)
<=> 5x^2 - 4x - 9 = 5x^2 + 100x + 500
<=> 5x^2 - 4x - 9 - 5x^2 - 100x - 500 = 0
<=> -104x - 509 = 0
<=> -104x = 509
<=> x = -509/104
Vậy S = { -509/104 }
\(\left(x-3\right)^3-2\left(x-1\right)=x\left(x-2\right)^2-5x^2\)
\(\Leftrightarrow x^3-9x^2+27x-27-2x+2=x\left(x^2-4x+4\right)-5x^2\)
\(\Leftrightarrow x^3-9x^2+25x-25=x^3-4x^2+4x-5x^2\)
\(\Leftrightarrow x^3-9x^2+25x-25=x^3-9x^2+4x\)
\(\Leftrightarrow21x-25=0\Leftrightarrow x=\frac{25}{21}\)
