b, x^3 + 2x^2 + 2x + 1( ab - 1 )^2 + ( a + b )^2
Giải thích
b) Ta có x3 + 2x2 + 2x + 1 = ( x3 + 1 ) + ( 2x2 + 2x )
= ( x + 1 )( x2 - x + 1 ) + 2x( x + 1 ) = ( x + 1 )( x2 + x + 1 )
b) Ta có x3 + 2x2 + 2x + 1 = ( x3 + 1 ) + ( 2x2 + 2x )
= ( x + 1 )( x2 - x + 1 ) + 2x( x + 1 ) = ( x + 1 )( x2 + x + 1 )