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log10(x-15)+log10x=2
人气:854 ℃ 时间:2024-09-19 10:21:05
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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