de l'aide svp pour mon dm de maths

Exercice 1

1)
(4 + x)²
= 16 + 8x + x²
= x² + 8x + 16

2)
(x - 4)²
= x² - 8x + 16

3)
(x - 2) (x + 2)
= x² + 2x - 2x - 4
= x² - 4

4)
3 (x - 2) + 6 (4 - x)
= 3x - 6 + 24 - 6x
= 3x - 6x - 6 + 24
= - 3x + 18

5)
(2x - 1) (4 - x)
= 8x - 2x² - 4 + x
= - 2x² + 8x + x - 4
= - 2x² + 9x - 4

Exercice 2

1)
3x + 4xy
= x (3 + 4y)

2)
x² - 6x
= x (x - 6)

4)
(x + 1) (x + 2) + 5 (x + 2)
= (x + 2) (5 + (x + 1))
= (x + 2) (x + 6)

Exercice 1: développer

1)
 (4+x)²=
16+4x+4x+x²
16+8x+x²

2)
(x - 4)²
x²-4x-4x+16
x²-8x+16

3)
(x - 2) (x + 2)
= x² + 2x - 2x - 4
= x² - 4+16

4)
3 (x - 2) + 6 (4 - x)
= 3x - 6 + 24 - 6x
= 3x - 6x - 6 + 24
= - 3x + 18

5)
(2x - 1) (4 - x)
= 8x - 2x² - 4 + x
= - 2x² + 8x + x - 4
= - 2x² + 9x - 4

Exercice 2: Factoriser

1) 
3x + 4xy
= x (3 + 4y)

2)
x² - 6x
= x (x - 6)

3)
2x(x-1)+3x
x(2x+1)

4)
(x + 1) (x + 2) + 5 (x + 2)
= (x + 2) (5 + (x + 1)
= (x + 2) (x + 6)