0.5lg32/49 -4/3lg根号8+lg根号245=?
1个回答

1.=0.5(lg32-lg49)-4/3lg2^(3/2)+lg[7*5^(1/2)]

=0.5(5lg2-2lg7)-(4/3)*(3/2)lg2+lg7+1/2lg5

=2.5lg2-lg7-2lg2+lg7+0.5lg5

=0.5lg2+0.5lg5

=0.5(lg2+lg5)

=0.5lg10

=0.5

2.=2lg5+2lg2+lg5*lg(5*2^2)+(lg2)^2

=2(lg5+lg2)+lg5*(lg5+2lg2)+(lg2)^2

=2+(lg5)^2+2lg5*lg2+(lg2)^2

=2+(lg5+lg2)^2

=2+1

=3

3.=[lg2^(1/2)+lg3-lg10^(1/2)]/lg(9/5)

=lg[(2^0.5)*3/(10^0.5)]/(lg9-lg5)

=lg[3/(5^0.5)]/[2lg3-2lg5^0.5]

=(lg3-lg5^0.5)/2(lg3-lg5^0.5)

=1/2