Question

已知函数f(x)=|lgx|求f^2(5)十f(1/2)xf(50)的

Answer 1

解f(x)=|lgx|

知f^2(5)十f(1/2)xf(50)

=|lg5|^2十|lg1/2|x|lg50|

=（lg5）^2-lg1/2xlg50

=（lg5）^2+lg2xlg50

=（lg5）^2+lg2xlg(2×25)

=（lg5）^2+lg2x(lg2+lg25)

=（lg5）^2+lg2x(lg2+2lg5)

=（lg5）^2+2lg2xlg5+(lg2)^2

=(lg5+lg2)^2

=(lg10)^2

=1^2

=1