Bonjour,
distributivité et double distributivité.....
A = 3(4x +7) - (2x -7) (5x+10)
= 12x + 21 - (10x²+20x-35x-70)
= -10x² + 12x - 20x + 35x + 21 + 70
= -10x² + 27x + 91
B = 7x(2x − 5) − x(2x − 5)
= 14x² - 35x - 2x² + 5x
= 12x² - 30x
C = (2x +5)(3x -7)-2x(4-5x)
= 6x² - 14x + 15x - 35 - 8x + 10x²
= 16x² - 7x - 35
D = (2x - 5)(2x - 5)
= (2x-5)²
= (2x)² - 2(2x)(5) + 5² car (a-b)² = a²-2ab+b²
= 4x² - 20x + 25
E = (4x-5)(4x+5)
= (4x)² - 5² car (a+b)(a-b) = a²-b²
= 16x² - 25
je te laisse faire le dernier sachant (a+b)² = a²+2ab+b²
