bonjour
1 ) construction
2) 2 ( 2 x + 4 x + 1.5 ) = 4 x + 8 x + 3 = 12 x + 3
12 x + 3 = 18
12 x = 15
x = 15/12 = 1.25 cm
3 ) 3 ( 4 x + 1 ) = 12 x + 3
12 x + 3 = 12 x + 3
donc vrai