C = ( -5x + 4 )( 3x - 2 ) + ( -2x + 3 )( x - 2 )
C = -5x( 3x - 2 ) + 4( 3x - 2 ) - 2x( x - 2 ) + 3( x - 2 )
C = -15x2 + 10x + 12x - 8 - 2x2 + 4x + 3x - 6
C = -17x2 + 29x - 14
Với x = -2 ta có :
C = -17.(-2)2 + 29.(-2) - 14 = -140
D = ( x - 5 )( -3x + 1 ) - 3( x - 2 )( 2x - 1 )
D = x( -3x + 1 ) - 5( -3x + 1 ) - 3( 2x2 - 5x + 2 )
D = -3x2 + x + 15x - 5 - 6x2 + 15x - 6
D = -9x2 + 31x - 11
Với x = 1/3 ta có :
D = -9.(1/3)2 + 31.1/3 - 11 = -5/3