Bonjour,
A = ( 2 x – 3)(5 + 3 x ) - ( 4 x+5)(2x-3)
1) Calculer cette expression si x = -1.
(2*-1 -3) (5 +3*-1) -( 4*-1 +5) (2*-1 -3)=
(-2-3) ( 5-3) -( +1)( -5)=
-5*2 +5 = -10+5 = -5
2) Développer et réduire A.
10x +6x² -15 -9x -( 8x² -12x +10x -15)=
10x +6x² -15 -9x - 8x² +12x -10x +15=
-2x² +3x
3) Factoriser A.
( 2 x – 3)(5 + 3 x ) - ( 4 x+5)(2x-3)
(2x-3) (5+3x -4x -5)=
(2x-3) ( -x )