1.x
的n次方=5,y的n次方=3,
(xy)^(2n)=(x^n)^2 * (y^n)^2 = 5^2*3^2=25*9=225
2.
a²-9=(a+3)(a-3)
a²-3a=a(a-3)
公因式a-3
3
A=3x-2,B=1-2x,c=-5x
A·B+A·C=A(B+C)=(3X-2)(1-2X-5X)=(3X-2)(1-7X)=-(3X-2)(7X-1)=-21X^2+17X-2
4.
(-8)^2006 *(-0.125)^2007
=(8)^2006 *(0.125)^2006 * (-0.125)
=(8*0.125)^2006 * (-0.125)
=1*(-0.125)
=-0.125
5.
1.
(x-y+9)(x+y-9)
=[x-(y-9)]*[x+(y-9)]
=x^2-(y-9)^2
=x^2-y^2+18y-81
2.
(99X101+1)/(251-247)
=[(100-1)(100+1)+1] / 4
=(100^2-1+1)/4
=100*100/4
=100*25
=2500