`a) ( x^ 3 + 27)+ ( x + 3 )( x - 9 ) = 0 `
`to ( x + 3)(x^2-3x+9)+ ( x + 3 )( x - 9 ) = 0 `
`to ( x + 3)(x^2-3x+9+ x - 9 ) = 0 `
`to ( x + 3)(x^2-2x ) = 0 `
`to x( x + 3)(x-2 ) = 0 `
\(\to\left[ \begin{array}{l}x=0\\x=-3\\x=2\end{array} \right.\)
`b) 4( x − 2 )^ 2 = 25 ( 1 − 2 x ) ^2`
`to 4( x − 2 )^ 2- 25 ( 1 − 2 x ) ^2=0`
`to[ 2( x − 2 )]^ 2- [5 ( 1 − 2 x )] ^2=0`
`to[ 2( x − 2 )- 5 ( 1 − 2 x )] [2(x-2)+5(1-2x)]=0`
`to( 2x − 4- 5 + 10 x ) (2x-4+5-10x)=0`
`to( 12x − 9 ) (1-8x)=0`
`to3( 4x − 3 ) (1-8x)=0`
\(\to\left[ \begin{array}{l}x=\cfrac34\\x=\cfrac18\end{array} \right.\)
