1.(2a-5)(a-2)=_2a^2-9a+10__.
2.下列分解因式正確的是（C）
A.a^2-2b^2=(a+2b)(a-2b)
B.-x^2+y^2=(-x+y)(-x-y)
C.-a^2+9b^2=(-a-3b)(a-3b)
D.4x^2-y^2=(-2x-y)(2x+y)
3.下列由左邊到右邊的變形,屬于分解因式的變形是（C）
A.x^2-2=(x-1)(x+1)-1
B.(a+b)(a-b)=a^2-b^2
C.1-x^2=(1+x)(1-x)
D.4x^2-y^2=(-2x-y)(2x+y)
4.(-2a)*(a^2-a+1)= -2a^3+2a^2-2a
5.（x+1)(x+2)-(x-1)^2 =x^2+3x+2-x^2+2x-1=5x+1
6.ab+ad+bc+bd =題錯
7.x^2-2xy+y^2-1=(x-y+1)(x-y-1)
8.a^4-16 =(a^2+4)(a+2)(a-2)
9.(a^2+4)^2-16a^2 =(a-2)^2(a+2)^2
10.已知x^2+2x+y^2-6y+10=0,(x+1)^2+(y-3)^2=0,x=-1,y=3 x^4=1
11.x^2(a-1)+4(1-a)=(x+2)(x-2)(a-1)
12.(x^2+9)^2-36x^2=(x+3)^2( x-3)^2
13.(x+y+)^2-4(x+y-1) 題錯
14.(a+b)(a-b)-5(a^2-2b^2)= (-2a+3b)(-2a-3b)