Exercice 1 svp c'est pour demain

Exercice 1
A) 1/3 + 5/6 =2/6+5/6 = 7/6
B) 4/5 + 2/11 =44/55 + 10/55= 54/55
c)  -35/42 - -21/35 = -5/6 + 3/5= - 25/30+18/30= - 7/30
d) - - 56/-25 x -15/14= 56x15/25x14= 4x3/5=12/5

Exercice3
A) (6x+3) (2x - 1) =12x² - 6x +6x -3=12x²-3
si x=1/2....
A) 12x²- 3= 12(1/2)² -3=12/4 -3=3 -3=0

B) 3x (2x-5) - (2x²+6)= 6x² - 15x -2x² -6 =4x²-15x - 6
si x=1/2
B) 4x²-15x - 6 =4(1/2)²-15(1/2) - 6=1-15/2-6=1/2-15/2-12/2=-26/2= -13/2