1.6mn(3m+2n-1)
2.原式=(x^2)^2-2x^2y^2+(y^2)^2=(X^2-Y^2)^2=(x+y)^2(x-y)^2
3.6ab(y-x)^2〔2b+4ab+3(y-x)〕
4.(t-7/2)^2-1/4
5.(x-2y)(x-3y)
6.(m+n-3)(m+n+2)
7.(a^2+4a)^2+8(a^2+4a)+16=(a^2+4a+4)^2
8.原式=(1000-0.2)^2=1000^2+0.2^2-2*1000*0.2=999600.04
9.原式=(25+1/5)(25-1/5)=25^2-(1/5)^2=15624/25
10.原式=(1+1/2)(1+1/3)……(1+1/100)(1-1/2)(1-1/3)……(1-1/100)
=3/2*4/3*5/4……101/100*(1/2*2/3……99/100)
=101/2*1/100
=101/200
1)x^2-y^2=(x+y)(x-y)=3,所以,x-y=3
所以,4xy=(x+y)^2-(x-y)^2=-8,则xy=-2
x^2-xy+y^2=(x-y)^2+xy=9+(-2)=7
2)x^2+5xy+30y =x(x+5y)+30y=6x+30y=6(x+5y)=6*6=36
3)(1+1/x)^2=25/4,所以,x^2+1/x^2=17/4
(x-1/x)^2=x^2+1/x^2-2=9/4
所以,x-1/x=3/2或-3/2
x^2-1/x^2=(x+1/x)(x-1/x)=15/4或-15/4