a) 2log23=3
(zgodnie ze wzorem alogab=b )
4log25+log217=4log25⋅4log217=(22)log25⋅(22)log217=22log25⋅22log217=
=2log252⋅(2(−1)⋅(−1))log2172=2log225⋅(2−1)(−1)⋅log2172=
=25⋅(21)log21(72)−1=25⋅(21)log2172⋅(−1)=25⋅(21)log217−2=
=25⋅(21)log21(71)2=25⋅(21)log21(491)=25⋅491=4925
2log23=3>4925=4log25+log217
b) 0,0007=100007=(100007)21=(10000)21721=100007=1007≈1002,65=
=0,026
(31)log34−log319=(31)log34⋅(31)−log319=(3−1)log34⋅(31)log319−1=
=3(−1)⋅log34⋅(31)log31(91)=3log34−1⋅(31)log31(91)=34log31⋅91=41⋅91=
=361≈0,028
0,0007≈0,026<0,028≈(31)log34−log319
c) 6log61(23)+log69=6log61(23)⋅6log69=(6(−1)⋅(−1))log61(23)⋅9=(6−1)(−1)⋅log61(23)⋅9=
=(61)log61(23)−1⋅9=(61)3log612⋅9=32⋅9=318=6
(7)2log73+21log716=(7)2log73+(2⋅41)log716=(7)2log73+2⋅41log716=
=(7)2⋅(log73+41log716)=((7)2)log73+log71641=7log73+log71641=
=7log73+log7(24)41=7log73+log724⋅41=7log73+log72=7log7(3⋅2)=
=7log76=6
6log61(23)+log69=6=(7)2log73+21log716
d) 10−1+4log5=10−1⋅104log5=(101)⋅10log54=101⋅10log54=101⋅10log625=
=101⋅625=10625=2125=6221
25−21log212=25⋅2−21log212=32⋅2log212−21=32⋅2log2(121)21=32⋅2log2121=
=32⋅2log2(121)=32⋅2log2(4⋅31)=32⋅2log2(4⋅31)=32⋅2log2(231⋅33)=
=32⋅2log2(2⋅33)=32⋅2log2(63)=32⋅63=6323=3163≈
≈316⋅1,73=327,68=9,22(6)≈9
10−1+4log5=6221>9≈25−21log212