75%x 75%x y=25%

0.85x2.5+0.085x75=0.85x2.5+0.85x7.5=0.85*（2.5+7.5）=8.5或0.85x2.5+0.085x75=0.085x25+0.085x75=0.085*（25

化简：原式=(x^2y^2-4-2x^2y^2+4)/xy=-x^2y^2=-4/25再答：没事，加入我们团么

[(xy+2)(xy+2)-2(xy+1)+2]÷(xy)=[(xy+2)(xy+2)-2xy-2+2]÷(xy)=[(xy+2)(xy+2)-2xy]÷(xy)=[(xy)^2+4xy+4-2xy]

[xy²-4-2x²y²+4]/xy=[xy²-2x²y²]/xy=xy-2xy=-xy当x=10,y=-1/25时原式=-（10*-1/2

{[(xy+2)(xy-2)]-2x的平方y的平方+4}/(xy)=(x^2y^2-4-2x^2y^2+4)/(xy)=-x^2y^2/(xy)=-xy=-10/25=-2/5

=[(x^2y^2-4)-(2x^2y^2-4)]/xy=(x^2y^2-4-2x^2y^2+4)/xy=x^2y^2/xy=xy=10*-1/25=-2/5

[（xy+2）（xy-2）-2x2y2+4]÷（xy）=（x2y2-4-2x2y2+4）÷xy=-x2y2÷xy=-xy,当x=10,y=1/25时,原式=-2/5．

[(xy+2)(xy-2)-2x^2y^2+4]/(xy)=[(x^2y^2-4)-2x^2y^2+4]/(xy)=-x^2y^2/xy=-xy=-10*(-1/25)=2/5

令t=xy方程变为：[(t-2)^2+4t-4]/(-t)=(t^2-4t+4+4t-4)/(-t)=-t=-xy又x=10,y=-1/25-xy=-10*(-1/25)=2/5

[（xy-2)²+4xy-4]÷(xy)=(x²y²-4xy+4+4xy-4)÷(xy)=x²y²÷xy=xy=10×1/25=2/5

36+64x448x9968x10225x16x125x325x25+25x75=36+256=48×100-48×1=68×100+68×2=（25×16）×（125×3）=25×（25+75）=2

xdy=(y+xy)dxdy/y=((1+x)/x)dxln|y|=ln|x|+x+cy=±e^(ln|x|+x+c)其中c是常数再问：真还不理解我们是选择题：y=cxe^xy=c+x-x^2y=cs

{（xy-2）^2+4xy-4}/(-xy)={(xy-2)^2+2(xy-2)+1+2xy-1}/(-xy)={[(xy-2)+1]^2+2xy-1}/(-xy)={(xy-1)^2+2xy-1}/

(3x^2+2xy)/xy-(2x^2-xy)/xy=(3x^2+2xy-2x^2+xy)/xy=(x^2+3xy)/xy=x(x+3y)/xy=(x+3y)/y

24x75=1800（24÷60）x（75x60）=1800（24x3）x（75÷3）=180036x104=3744（36x4）x（104÷4）=3744（36÷4）x（104x4）=3744

89

36.5X2.5+2.65X75=36.5X2.5+(2.5+0.15)X(63.5+11.5)=36.5X2.5+63.5X2.5+2.5X11.5+0.15X75=(36.5+63.5)X2.5+

9.5x3/4+1/2x75%=9.5*0.75+0.5*0.75=（9.5+0.5）*0.75=10*0.75=7.5

[(xy-2)(-xy-2)-4(xy-1)^2]除以(-xy)=[-x²y²+4-4(x²y²-2xy+1)]÷(-xy)=(-x²y²+

即(10x+y)*(10y+x)=2268101xy+10x²+10y²=2268因为后面的10x²+10y²只可能是整十的数,所以2268中的个位8要靠101