(1)计算log3
(2)已知x
|
解(1)log3
+lg25+lg4+7log724 27 3
=log3
+lg52+lg22+23 3 4 3
=-
+2(lg5+lg2)+21 4
=
;15 4
(2)由x
+x-1 2
=3,1 2
得:(x
+x-1 2
)2=9,1 2
所以,x+2+x-1=9,
故x+x-1=7,
所以,
=2 x+x-1+3
=2 7+3
.1 5
(1)计算log3
(2)已知x
|
解(1)log3
+lg25+lg4+7log724 27 3
=log3
+lg52+lg22+23 3 4 3
=-
+2(lg5+lg2)+21 4
=
;15 4
(2)由x
+x-1 2
=3,1 2
得:(x
+x-1 2
)2=9,1 2
所以,x+2+x-1=9,
故x+x-1=7,
所以,
=2 x+x-1+3
=2 7+3
.1 5