Bonjour,
A = 5x - (3 - 4x²+ 2x) - 3x²+ 4
= 5x-3+4x² -2x -3x² +4
= x² +3x +1
B) 10 + 4x + (-8x² - 2x + 7) + 2x²
= 10 +4x -8x² +2x -7 +2x²
= -6x² +6x +3
Développer puis réduire les expressions suivantes :
C = 2(x - 4)
= 2x-4
D = (x + 3)(2x + 7)
= 2x² +7x +6x +21
= 2x² +13x +21
E = 5x - 3(x + 4) + (x - 2)(6 + x)
= 5x -3x-12 + 6x +x² -12 -2x
= x² +4x -24