Chuyên đ luy n thi đ i h c: Ph Gi i ph ng trình-b t ph ng trình: 1) log3x + log9x + log27x = 11 ) ( ng pháp đ a v c s 4) log 1 + x − x − ≤ 7) 1 + lg + lg = lg 27 − x 2x ( 3) log x − = log (x - 1) 5) log3x.log9x.log27x.log81x = 6) log log x − > 8) log x = + log − log ( 11) log x − − x + ≥ −1 3 14) log x + log x + log x = 10) + log x log (10 − x ) = log x 13) log2x.log3x = log2x + log3x3 – ) 2) log ( x + x − 3) = 9) log ) 2 ) ( x2 − − x +1 ≤ 12) logx(2x2 – 7x +12) = 15) log x ≤ log x 17) log 5 − = log x 16) log x − + = log x + 3 1 1 18) log log x − = 5 =1 21) log x − − 1 x x 19) log 1 − + log 2 − = 2 2 20) + 22) log ( x + )2 + log x + x + = 23) log2x + log3x + log4x = log10x 24) log3(5x2 + 6x + 1) ≤ 25) log4(log2x) + log2(log4x) = 26) log2(4.3x - 6) - log2(9x - 6) = 27) 2log (x 28) x + lg(1 + x ) = x lg + lg 29) log3(4.3x – 1) = 2x – 30) log (log x) = −1 + log sin x = 15 + log15 cos x −6 x +9 31) + log − = log x log (12 − x) log x 32) 34) 1) log ( x + x ) − + log ( 2x + ) = log (5 − x ) + log − x = 35) log x + log x = log ( 40) lg 10 lg (x ( − 21 ) ) − = lg x − lg ) 2x − 1