3.
A=(x-3)(x-2)+5(x-3)
=(x-3)(x-2+5)
=(x-3)(x+3)
B=3(5-9x)-(5-9x)(1-3x)
=(5-9x)(3-1+3x)
=(5-9x)(2+3x)
C=(2x-5)(7x+5)-(2x-5)^2
=(2x-5)(7x+5-2x+5)
=(2x-5)(5x+10)
4.
A=4(x-2)-(x-2)(3x+1)
=(x-4)(4-3x-1)
=(x-4)(3-3x)
B=5-9x+(5-9x)(1-3x)
peu pas être factoriser
C=(3x-7)^2-(1-2x)(3x-7)
=(3x-7)(2-1+2x)
=(3x-7)(1+2x)
5.
a=(2x+3)(5x-1)-(2x+3)(4x-7)
=(2x+3)(5x-1-4x+7)
=(2x+3)(x+6)
b=(3x-5)^2-3(2x+7)(3x-5)
=(3x-5)^2-(6x+21)(3x-5)
=(3x-5)(2-6x-21)
=(3x-5)(-6x-19)
c=(2x-4)(-3x+7)-5(2x-4)+(2x-4)(4x+3)
=(2x-4)(-3x+7-5+4x+3)
=(2x-4)(x+5)
