Question

1.计算：lg 25+2/3lg 8+lg 5×lg 20+lg^(2) 2

Answer 1

1,lg25+2/3lg8+lg5*lg20+lg^22

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

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

=2lg10+(lg5+lg2)^2

=2+1^2

=3

2,设f(x)=ax+b

3f(x+1)-2f(x-1)

=3a(x+1)+3b-［2a(x-1)+2b］

=3ax+3a+3b-2ax+2a-2b

=ax+5a+b

=2x+17

所以,a=2

5a+b=17,b=7

f(x)=2x+7