1.（lg2）^3+(lg5)^3+3lg2*lg5=2.若lg(x-y)+lg(x+2y)=lg2+lgx+lgy,则x/y=

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1.（lg2）^3+(lg5)^3+3lg2*lg5=2.若lg(x-y)+lg(x+2y)=lg2+lgx+lgy,则x/y=

1.（lg2）^3+(lg5)^3+3lg2*lg5=2.若lg(x-y)+lg(x+2y)=lg2+lgx+lgy,则x/y=
1.（lg2）^3+(lg5)^3+3lg2*lg5=
2.若lg(x-y)+lg(x+2y)=lg2+lgx+lgy,则x/y=

1.（lg2）^3+(lg5)^3+3lg2*lg5=2.若lg(x-y)+lg(x+2y)=lg2+lgx+lgy,则x/y=
1.设x=lg2,y=lg5,则x+y=lg2+lg5=lg10=1
原式=x^3+y^3+3xy
=(x+y)(x^2-xy+y^2)+3xy
=x^2-xy+y^2+3xy
=x^2+2xy+y^2
=(x+y)^2
=1
2.
lg(x-y)+lg(x+2y)=lg2+lgx+lgy
lg(x-y)(x+2y)=lg2xy
(x-y)（x+2y)=2xy
x^2+xy-2y^2=2xy
x^2-xy-2y^2=0
设x/y=k
k^2y^2-ky^2-2y^2=0
(k^2-k-2)Y^2=0
k^2-k-2=0
(k+1)(k-2)=0
k=-1,k=2
x/y=-1（舍）,x/y=2

lg2(lg5-lg2)-lg5(lg5+3lg2)等于 （lg2）^3+(lg5)^3+3lg2*lg5等于? (lg2)^3+(lg5)^3+3*lg2*lg5 (lg2)³+(lg5)³+3lg2×lg5 3+lg5+(lg2)^2 3lg2-lg5= 对数lg2*lg5=?2lg（5）+2/3 lg8+lg5*lg20+lg2 =lg5^2+lg8^(2/3)+lg5*(lg4+lg5)+lg2 =lg100+lg5+2lg2*lg5+lg2 =2+(lg5+lg2) =2+1 =3 第二个等号lg5*(lg4+lg5)为什么=lg5+2lg2*lg5 (lg2)^3+(lg5)^3+3lg2lg5怎么算=（lg5+lg2）[（lg5)²-lg5lg2+(lg2)²]+3lg5lg2为什么 3lg5＊lg2+（3lg2）＾2=? (lg2)^3+(lg5)^3+3lg2*lg5怎么算RT (lg2)^3+3lg2·lg5+(lg5)^3 怎么算? (lg2)^3+(lg5)^3+3lg2*lg5 这些怎么算. (lg2)^3+3lg2·lg5+(lg5)^3 怎么算? (lg2)^3+(lg5)^3+3lg2*lg5的值为? （lg2)^3+3lg2乘lg5+(lg5)^3 求解3lg5+3lg2*lg5+3lg2^2~ (lg2)³+(lg5)³+3lg2×lg5(等于多少?) (lg2)³+(lg5)³+3lg2×lg5(怎么算呀,