Đáp án:
Bài 1 :
a, A= 3x²+6x-9
=3x²-3x+9x-9
= (3x²-3x)+(9x-9) =3x(x-1)+9.(x-1)=(x-1).(3x+9)=3.(x-1).(x+3)
c, C= -8x²+24x-16
= (-8x²+8x)+(16x-16)
= -8x.(x-1)+16.(x-1)
=(x-1).(-8x+16)
=-8.(x-1).(x-2)
e, E= 17x²-13x-94
= (17x²+34x)-(47x+94)
=17x.(x+2)-47.(x+2)
=(x+2).(17x-47)
f, F=x²-5x+6
= (x²-2x)-(3x-6)
=x.(x-2)-3.(x-2)
=(x-2).(x-3)
g, G=2x²+5x+2
= (2x²+4x)+(x+2)
= 2x.(x+2)+(x+2)
=(x+2).(2x+1)
Bài 2 :
c, C=9x²-16 =(3x-4).(3x+4)
d, D=25-4x² = (5-2x).(5+2x)
e, E= (3x+1)²-4.(x-2)²= (3x+1)²-(2x-4)²=(3x+1-2x+4).(3x+1+2x-4)=(x+5).(5x-3)
f, F=9x²-$\frac{4}{81}$ = 9x²-$\frac{2²}{9²}$ = (3x-$\frac{2}{9}$ ).(3x+$\frac{2}{9}$ )
g, G= (4x²-3x-18)²-(4x²+3x)²=(4x²-3x-18+4x²+3x).(4x²-3x-18-4x²-3x)= (8x²-18).(-6x-18)=-12.(x²-9).(x+3)
h, H=(2x+3)²-9.(2x-3)²=(2x+3)²-(6x-9)²=(2x+3+6x-9).(2x+3-6x+9)=(8x-6).(-4x+12)=-8.(4x-3).(x-3)
j, J=x^4 -1= (x²-1).(x²+1)=(x-1).(x+1).(x²+1)
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