1) D= (2x-3)(5x+4)+(2x-3)²= (2x-3) [(5x+4)+(2x-3)]
= (2x-3)[7x+1]
2) (2x-3)(7x+1)=0
<=>2x-3 = 0
ou 7x+1 = 0
<=> 2x = 3
ou 7x=-1
S={-1/7,3/2)
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1) D=9x²-1
a) Utilise a²-b² = (a+b)(a-b)
b) D = (3x+1)(3x-1)
2) E = (3x+1)² + 9x²-1
a) E = 9x²+1+6x+9x²-1=18x²+6x
b) E = 6x (3x+1)
c) 6x(3x+1)=0
6x=0
ou (3x+1)=0
<=> x=0
ou 3x=-1
S = {-1/3,0}