Bonjour,
Exercice 1 :
1) 5(2x-3)²-(5x-2)x(5x+2)
5(4x²-12x+9)-(25x²-4)
20x²-60x+45-25x²-4)
=-5x²-60x+49
8(2x-1)(2x+1)-4(3x-1)²
8(4x²-1)-4(9x²-6x+1)
32x²-8-36x²+24x-4
-4x²-12+24x
=-4x²+24x-12
2)(5x-1)-2(5x-1)(x+3)
(5x-1(1-2(x+3))
(5x-1)(1-2x-6)
=(5x-1)x(-5-2x)
9x²-24x+16
=(3x-4)²
(x-1)²-(x+1)²
(-2)x2x
=-4x
Exercice 2 :
1.4x²-9-(2x+3)(x-1)
4x²-9-(2x²-2x+3x-3)
4x²-9-(2x²+x-3)
4x²-9-2x²-x+3
2x²-6-x
=2x²-x-6
2.4x²-9-(2x+3)(x-1)
4x²-9=(2x-3)x(2x+3)
(2x-3)(2x+3)-(2x+3)(x-1)
(2x+3)(2x-3-(x-1))
2x+3)x(2x-3-x+1)
=(2x+3)(x-2)
3.Pour x = 3/2
4+(3/2)²-9-(2+3/2+3)(3/2-1)
4+9/4-9-(5+3/2)x1/2
4+9/4-9-13/2x1/2
4+9/4-9-13/4
-5-1
=-6
Pour x =-4
4-4²-9-(2-4+3)(-4-1)
4-16-9-1x(-5)
4-16-9+5
=-16
Et pour l'exercice 3 je te laisse le faire , tu dois faire Pytahgore.
