Bonjour ;

1.

a.

1/x = 4 , donc : x = 1/4 .

b.

1/x = - 1/2 , donc : x = - 2 .

c.

1/x = - 5 , donc : x = - 1/5 .

2.

a.

3 + 1/x = 5 ; donc : 1/x = 2 ; donc : x = 1/2 .

b.

1/(x + 1) = 2 ; donc : x + 1 = 1/2 ; donc : x = - 1/2 .

c.

5/(2x - 1) = 1 ; donc : 2x - 1 = 5 ; donc : 2x = 6 ; donc : x = 3 .

ex 50

1/x = 4

=> 1 = 4x

x = 1/4

1/x = -1/2

-x = 2

x = -2

1/x = - 5

1 = -5x

x = -1/5

3 + 1/x = 5

1/x = 2

1 = 2x

x = 1/2

(1/x+1) = 2

1 = 2 (x+1)

2x + 2 = 1

2x = -1

x = -1/2

(5/2x-1) = 1

5 = 2x-1

2x = 6

x=3