Răspuns :
x²+6x+8= x²+6x+9-1= (x+3)²-1= (x+3-1)(x+3+1)= (x+2)(x+4)
(2x+3)²-4= (2x+3-2)(2x+3+2)=(2x+1)(2x+5)
x²-9x+20=x²-5x-4x+20= x(x-5) -4(x-5) =(x-5)(x-4)
x²+3x-10=x²+2x-5x-10= x(x+2)-5(x+2)=(x+2)(x-5)
(2x+3)²-4= (2x+3-2)(2x+3+2)=(2x+1)(2x+5)
x²-9x+20=x²-5x-4x+20= x(x-5) -4(x-5) =(x-5)(x-4)
x²+3x-10=x²+2x-5x-10= x(x+2)-5(x+2)=(x+2)(x-5)