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log10(x-15)+log10x=2
人气:472 ℃ 时间:2020-06-18 06:14:50
解答
lg(x-15)+lgx=2
=> lgx(x-15)=2
=> x²-15x=10²
=> (x-20)(x-5)=0
=> x=20 或 x=-5(舍去)
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