问题标题:
1.设3^a=4^b=36,则2/a+1/b=?2.已知log8^9=a,log2^5=b,则lg3=?3.若lga、lgb是方程2x^2-4x+1=0的两个实数根,求lg(ab)(lga/b)^2的值
问题描述:
1.设3^a=4^b=36,则2/a+1/b=?
2.已知log8^9=a,log2^5=b,则lg3=?
3.若lga、lgb是方程2x^2-4x+1=0的两个实数根,求lg(ab)(lga/b)^2的值
奔粤阳回答:
3^a=4^b=36
==>a=log336=log34+log39=2log32+2
==>b=log436=log44+log49=1+log23
==>2/a+1/b=1/(1+log32)+1/(1+log23)=lg3/(lg2+lg3)+lg2/(lg2+lg3)=1
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