Réponse :
Explications étape par étape
Bonjour
1) compléter la pyramide :
...................9
..........|...A...|...B...|
......| x ......| 5 ..| 3x...|
A = x + 5
B = 5 + 3x
9 = A + B
9 = x + 5 + 5 + 3x
9 = 10 + 4x
2) déterminer x :
9 - 10 = 4x
-1 = 4x
x = -1/4
x = -0,25
A = x + 5 = -1/4 + 5 = -1/4 + 20/4 = 19/4 = 4,75
B = 3x + 5 = 3 * (-1/4) + 5 = -3/4 + 20/4 = 17/4 = 4,25
3x = 3 * (-1/4) = -3/4
........................9
..........|...4,75...|...4,25...|
......| -1/4 ....| 5 .......|..... -3/4...|
