Examples with solutions for Change-of-Base Formula for Logarithms: Using variables

Exercise #1

log4x9log4xa= \frac{\log_{4x}9}{\log_{4x}a}=

Video Solution

Answer

loga9 \log_a9

Exercise #2

log89alog83a= \frac{\log_89a}{\log_83a}=

Video Solution

Answer

log3a9a \log_{3a}9a

Exercise #3

ln4x= \ln4x=

Video Solution

Answer

log74xlog7e \frac{\log_74x}{\log_7e}

Exercise #4

2log7(x+1)log7e=ln(3x2+1) \frac{2\log_7(x+1)}{\log_7e}=\ln(3x^2+1)

x=? x=\text{?}

Video Solution

Answer

1,0 1,0

Exercise #5

log4(x2+8x+1)log48=2 \frac{\log_4(x^2+8x+1)}{\log_48}=2

x=? x=\text{?}

Video Solution

Answer

4±79 -4\pm\sqrt{79}

Exercise #6

Find X

log84x+log8(x+2)log83=3 \frac{\log_84x+\log_8(x+2)}{\log_83}=3

Video Solution

Answer

1+312 -1+\frac{\sqrt{31}}{2}

Exercise #7

What is the domain of X so that the following is satisfied:

\frac{\log_{\frac{1}{8}}2x}{\log_{\frac{1}{8}}4}<\log_4(5x-2)

Video Solution

Answer

\frac{2}{3} < x

Exercise #8

log47×log149aclog4b= \frac{\log_47\times\log_{\frac{1}{49}}a}{c\log_4b}=

Video Solution

Answer

logbc1a \log_{b^c}\frac{1}{\sqrt{a}}

Exercise #9

log8x3log8x1.5+1log49x×log7x5= \frac{\log_8x^3}{\log_8x^{1.5}}+\frac{1}{\log_{49}x}\times\log_7x^5=

Video Solution

Answer

12 12

Exercise #10

logx16×ln7lnxln4logx49= \log_x16\times\frac{\ln7-\ln x}{\ln4}-\log_x49=

Video Solution

Answer

2 -2

Exercise #11

logx4+logx30.25xlogx11+x=3 \frac{\log_x4+\log_x30.25}{x\log_x11}+x=3

x=? x=\text{?}

Video Solution

Answer

2 2

Exercise #12

1log2x6×log236=log5(x+5)log52 \frac{1}{\log_{2x}6}\times\log_236=\frac{\log_5(x+5)}{\log_52}

x=? x=\text{?}

Video Solution

Answer

1.25 1.25