(lgx)^2-lg x^2-3=0 求x (2)log9 27=?(3)log3(log4 64)=?(4)log(2+根号3) (2-根号3)

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(lgx)^2-lg x^2-3=0 求x (2)log9 27=?(3)log3(log4 64)=?(4)log(2+根号3) (2-根号3)
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(lgx)^2-lg x^2-3=0 求x (2)log9 27=?(3)log3(log4 64)=?(4)log(2+根号3) (2-根号3)
(lgx)^2-lg x^2-3=0 求x
(2)log9 27=?
(3)log3(log4 64)=?
(4)log(2+根号3) (2-根号3)

(lgx)^2-lg x^2-3=0 求x (2)log9 27=?(3)log3(log4 64)=?(4)log(2+根号3) (2-根号3)
x<4是减函数
所以开口向上
a>0
且对称轴x=-2(a-1)/(2a)在定义域右边
所以-2(a-1)/(2a)>=4
(a-1)/a<=-4
a>0
所以a-1<=-4a
a<=1/5
所以0

(lgx)^2-lg x^2-3=0
(lgx)^2-2lgx-3=0
(lgx-3)(lgx+1)=0
lgx=3,lgx=-1
x=1000,x=1/10

ggiutiu