作业帮(lg2)x(lg2)x(lg2)+(lg5)^3+3xlg2xlg5=?
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(lg2)x(lg2)x(lg2)+(lg5)^3+3xlg2xlg5=?
(lg2)x(lg2)x(lg2)+(lg5)^3+3xlg2xlg5=?
(lg2)x(lg2)x(lg2)+(lg5)^3+3xlg2xlg5=?
(lg2)*(lg2)*(lg2)+(lg5)^3+3*lg2*lg5
=(lg2+lg5)*(lg2*lg2+lg5*lg5-lg2*lg5)+3*lg2*lg5
=lg2*lg2+lg5*lg5-lg2*lg5+3*lg2*lg5
=lg2*lg2+lg5*lg5+2*lg2*lg5
=(lg2+lg5)^2
=1