Diketahui log2=0,2143 ; log3=0,3747 dan log5=0,5631\log2=0,2143\ ;\ \log3=0,3747\ dan\ \log5=0,5631log2=0,2143 ; log3=0,3747 dan log5=0,5631. Hasil dari log8+log9−log25\log8+\log9-\log25log8+log9−log25 adalah ....
2,5158
0,2634
1,017
-1,2354
0,2661
Gunakan sifat logaritma anlogam=mn×aloga^{a^n}\log a^m=\frac{m}{n}\times^a\log aanlogam=nm×aloga
⇔log8+log9−log25\Leftrightarrow\log8+\log9-\log25⇔log8+log9−log25
⇔log23+log32−log52\Leftrightarrow\log2^3+\log3^2-\log5^2⇔log23+log32−log52
⇔ 3×log2+2×log3−2×log5\Leftrightarrow\ 3\times\log2+2\times\log3-2\times\log5⇔ 3×log2+2×log3−2×log5
Substitusi log2=0,2143 ; log3=0,3747 dan log5=0,5631\log2=0,2143\ ;\ \log3=0,3747\ dan\ \log5=0,5631log2=0,2143 ; log3=0,3747 dan log5=0,5631
⇔ 3×0,2143+2×0,3747−2×0,5631=0,2661\Leftrightarrow\ 3\times0,2143+2\times0,3747-2\times0,5631=0,2661⇔ 3×0,2143+2×0,3747−2×0,5631=0,2661