bonjour
f ( 0 )= 5 et f( 3 ) = 0
( 0 - 5 ) / ( 3 - 0 ) = - 5 /3 donc ax = - 5 x / 3
f ( 3) = 0
⇔ 3 * - 5/3 + b = 0
⇔ - 15/3 + b = 0
⇔ b = 15/3 = 5
f (x) = - 5 x /3 + 5
f (x ) > 5
- 5 x /3 + 5 > 5
- 5 x /3 > 5 - 5
- 5 x > 0
x < 0
f (x) ≤ 0
- 5 x /3 + 5 ≤ 0
- 5 x / 3 ≤ - 5
x ≥ - 15
g ( 2 ) = 10 et g ( - 1 ) = 0
( 0 - 10 ) / ( - 1 - 2 ) = - 10 / - 3 donc ax = 10 x / 3
g ( 2) = 10
2 * 10/3 + b = 10
⇔ 20/3 + b = 10
⇔ b = 10 - 20 /3 = ( 30 - 20 ) / 3 = 10 /3
g (x) = 10 x /3 + 10 /3
f (x) = g ( x)
- 5 x /3 + 5 = 10 x /3 + 10 /3
- 5 x /3 - 10 x / 3 = 10 /3 - 15 /3
- 15 x /3 = - 5/3
- 15 x = - 5
x = 3
g (x) < g (x ) simple à déduire puisque tu connais f (x) = g (x)
