Sagot :
je suppose qu'il y avait une faute de frappe
f= (2x+3)(5-x)-(2x+3)² = (2x+3)(5-x-2x-3) = (2x+3)(2-3x)
(2x+3)(2-3x)=0 => 2x + 3 = 0 => x = -3/2
=> 2 - 3x = 0 => x = 2/3
f(3) = 9.-7 = -63
factoriser m= (3x-4)²-(x-5)(3x-4) = (3x-4)(3x-4-x+5) = (3x-4)(2x+1)
(2x+1)(3x-4)=0 => 2x+1 = 0 = x = -1/2
=> 3x - 4 = 0 => x = 4/3
pour x = 2: m = 5.2 = 10
(2x+3) ((5-x)-(2x-3))
(2x+3)(5-x-2x-3)
(2x+3) (-3x+2)
2x+3=0 ou 2-3x=0
x=-1,5 ou x=2/3