Exercices complémentaires

Série A

3) Mets le ou les facteurs communs en évidence.

a)

 

5x + 5y

 

= 5 . x + 5 . y

= 5 . (x + y)

b)

 

12a – 8b

 

= 4 . 3a – 4 . 2b

= 4 . (3a – 2b)

 

xy + xz

 

= x . y + x . z

= x . (y + z)

 

15ab – 10ac

 

= 5a . 3b – 5a . 2c

= 5a . (3b – 2c)

 

5x + 10y

 

 

= 5 . x + 5 . 2y

= 5 . (x + 2y)

 

 

– 4a – 6c

 

 

= – 4a + (– 6c)

= (– 2) . 2a + (– 2) . 3c

= (– 2) . (2a + 3c)

 

15a + 25b

 

= 5 . 3a + 5 . 5b

= 5 . (3a + 5b)

 

– 2x + 4y

 

= 2 . (– x) + 2 . 2y

= 2 . (– x + 2y)

 

6ab + 9ac

 

= 3a . 2b + 3a . 3c

= 3a . (2b + 3c)

 

18a – 24b

 

= 6 . 3a – 6 . 4b

= 6 . (3a – 4b)

c)

 

x2 + xy

 

= x . x + x . y

= x . (x + y)

d)

8a2 – 12a

 

= 4a . 2a – 4a . 3

= 4a . (2a – 3)

 

5x + 2x2

 

= x . 5 + x . 2x

= x . (5 + 2x)

 

– 15x + 10x2

 

= 5x . (– 3) + 5x . 2x

= 5x . (– 3 + 2x)

 

8a2 + 12a

 

 

= 4a . 2a + 4a . 3

= 4a . (2a + 3)

 

 

– 45a2 – 27a

 

 

= – 45a2 + (– 27a)

= (– 9a) . 5a + (– 9a) . 3

= (– 9a) . (5a + 3)

 

16x2 + 24x

 

= 8x . 2x + 8x . 3

= 8x . (2x + 3)

 

8a 16a2

 

= 8a . 1 – 8a . 2a

= 8a . (1 – 2a)

 

3a2 + 13a

 

= a . 3a + a . 13

= a . (3a + 13)

 

x2 – 3x

 

= x . x – x . 3

= x . (x – 3)