Question

高一数学必修一 74页 A组

3.计算:
(1) loga2+loga2分之1 (a>0,且a不等於1)
(3)log4分之1-lg25
4已知lg2=a,lg3=b,求下列各式的值:
(1) lg6 (4)lg2分之3

5.已知x的对数,求x
(1)lgx=lga+lgb
(4) logax=2分之1logab-logac

Answer 1

3、 (1)log(a)2+log(a)1/2
=log(a)2*1/2
=log(a)1
=0
(3)lg1/4-lg25
=lg1/4*25
=lg1/100
=-2
4.(1)lg6=lg(2*3)
=lg2+lg3
=a+b
(2)lg3/2=lg3-lg2
=b-a
5.(1)lgx=lga+lgb
lgx=lg(a*b)
x=ab
(2)log(a)x=1/2log(a)b-log(a)c
2log(a)x=log(a)b/c
log(a)x^2=log(a)b/c
x^2=b/c
x=根号下c分之b
纯手打，望采纳谢谢

Answer 2

3(1) 0
(3) -2

4(1)ab
(4)a/b

5(1)x=ab
(4)(a/c)的2分之1次方（开根号）