Bonjour,

Identités remarquables :

(a + b)² = a² + 2ab + b²

(a - b)² = a² - 2ab + b²

(a + b)(a - b) = a² - b²

A = (2x - 4)(3x - 5) + (5x - 1)²

A = 2x * 3x + 2x * (-5) - 4 * 3x - 4 * (-5) + (5x)² - 2 * 5x * 1 + 1²

A = 6x² - 10x - 12x + 20 + 25x² - 10x + 1

A = 25x² + 6x² - 10x - 12x - 10x + 20 + 1

A = 31x² - 32x + 21

B = (3y - 7)(3y + 7) - (2y + 5)²

B = (3y)² - 7² - ((2y)² + 2 * 2y * 5 + 5²)

B = 9y² - 49 - (4y² + 20y + 25)

B = 9y² - 49 - 4y² - 20y - 25

B = 9y² - 4y² - 20y - 49 - 25

B = 5y² - 20y - 74

C = (5z + 2)² - (6z - 5)²

C = (5z)² + 2 * 5z * 2 + 2² - ((6z)² - 2 * 6z * 5 + 5²)

C = 25z² + 20z + 4 - (36z² - 60z + 25)

C = 25z² + 20z + 4 - 36z² + 60z - 25

C = 25z² - 36z² + 20z + 60z + 4 - 25

C = -11z² + 80z - 21

Verified answer

Bonjour,

Développer:

A= (2x-4)(3x-5)+(5x-1)²

A= 6x²-12x-10x+20+25x²-10x+1

A= 31x²-32x+21

B= 9y²-49-(4y²+20y+25)= 9y²-49-4y²-20y-25= 5y²-20y-74

Pareil pour la C.