bonjour je n’ai pas compris cet exercice pouvez-vous m’aider svp?

Bonsoir,

1)

f (x) = - 2x + 8

f (0) = - 2 * 0 + 8

f (0) = 8

2)

g (x) = - 5 (x + 1)

g (13) = - 5 (13 + 1)

g (13) = 5 * 14

g (13) = 70

3)

f (x) = - 2x + 8 = 11

- 2x = 11 - 8

- 2x = 3

x = - 3/2

4)

g (x) = - 5 (x + 1)

- 5 (x + 1) = 0

- 5x - 5 = 0

- 5x = 5

x = - 5/5

x = - 1

5)

a) f (x) = 7

- 2x + 8 = 7

- 2x = 7 - 8

- 2x = - 1

x = 1/2

b) g (x) = - 5

- 5 (x + 1)

= - 5 (- 5 + 1)

= - 5 * - 4

= 20

c) f (x) = g (x)

- 2x + 8 = - 5 (x + 1)

- 2x + 8 = - 5x - 5

- 2x + 5x = - 5 - 8

3x = - 13

x = - 13/3