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exercice 6

(12x+3)(2x-7) -5x(2x-7)

24x²-84x+6x-21-10x²+35x

14x²-41x-21

factoriser

(12x+3)(2x-7) -5x(2x-7)

(2x-7)(12x+3-5x)

(2x-7)(7x+3)

resoudre d =0

2x-7 =0                            7x+3 =0

2x = 7                                7x = -3

x = 7/2                                  x =  -3/7

solution (-3/7 ; 7/2)