Réponse :

bonsoir

f (x) = 3 x - 5

f ( - 7 )  = - 21 - 5 = - 26

f (2.1 ) = 6.3 - 5 = 1.3

f ( 2/5 ) = 6/5 - 5  = 6/5 - 25/5 = -  19/5

3 x - 5 = 16

3 x = 16 + 5

3 x = 21

x = 7

3 x - 5 = 5

3 x = 5 + 5

3 x = 10

x = 10/3

f (x) = 2 x /5 - 1 /3

f ( 5 ) = 10 /5 - 1 /3 = 2 - 1/3 = 6/3 - 1 /3 = 5/3

f ( - 15 ) = - 30 /5 - 1/3 = - 6 - 1/3 = - 18/3 - 1/3 = - 19/3

f ( 5/4 ) =  10/20 - 1/3 = 30/60 - 20/60 = 10/60 = 1/6

2 x /5 - 13/3 = 2 /3

6 x /15 - 65/15 = 10/15

6 x = 10 + 65

6 x = 75

x = 75/6  = 12.5

2 x /5 - 1 /3 = 0

6 x /15 - 5/15 = 0

6 x = 5

x = 5/6  

Explications étape par étape :