bonjour
f ( 0) = 200
f ( 4) = 400
( 400 - 200 ) / ( 4 - 0 ) = 200 /4 = 50
ax = 50 x
f ( 0) = 200 donc b = 200
f (x) = 50 x + 200
d'où f ( 4 ) = 4 * 50 + 200 = 400
g ( 0 ) = 40
g ( 100) = 0
( 0 - 40 ) / ( 100 - 0 ) = - 40/100 = - 4 /10
ax = - 4 x /10
g ( 0 ) = 40 donc b = 40
g (x) = - 4 x / 10 + 40
d'où g (200) = 200 * - 4/10 + 40 = - 800 /10 + 40 = - 80 + 40 = - 40