The Sum of Logarithms: Resulting in a quadratic equation

Examples with solutions for The Sum of Logarithms: Resulting in a quadratic equation

Exercise #1

log7x+log(x+1)log7=log2xlogx \log7x+\log(x+1)-\log7=\log2x-\log x

?=x ?=x

Video Solution

Step-by-Step Solution

Defined domain

x>0

x+1>0

x>-1

log7x+log(x+1)log7=log2xlogx \log7x+\log\left(x+1\right)-\log7=\log2x-\log x

log7x(x+1)7=log2xx \log\frac{7x\cdot\left(x+1\right)}{7}=\log\frac{2x}{x}

We reduce by: 7 7 and by X X

x(x+1)=2 x\left(x+1\right)=2

x2+x2=0 x^2+x-2=0

(x+2)(x1)=0 \left(x+2\right)\left(x-1\right)=0

x+2=0 x+2=0

x=2 x=-2

Undefined domain x>0

x1=0 x-1=0

x=1 x=1

Defined domain

Answer

1 1

Exercise #2

log2x+log2x2=5 \log_2x+\log_2\frac{x}{2}=5

?=x

Video Solution

Answer

8 8

Exercise #3

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 #4

log3x+log(x1)=3 \log3x+\log(x-1)=3

?=x ?=x

Video Solution

Answer

18.8 18.8

Exercise #5

log4x+log4(x+2)=2 \log_4x+\log_4(x+2)=2

Video Solution

Answer

1+17 -1+\sqrt{17}

Exercise #6

?=a

ln(a+5)+ln(a+7)=0 \ln(a+5)+\ln(a+7)=0

Video Solution

Answer

6+2 -6+\sqrt{2}

Exercise #7

x=? x=\text{?}

ln(x+5)+lnxln4+ln2x \ln(x+5)+\ln x≤\ln4+\ln2x

Video Solution

Answer

0 < X \le 3

Exercise #8

\log_{0.25}7+\log_{0.25}\frac{1}{3}<\log_{0.25}x^2

x=? x=\text{?}

Video Solution

Answer

-\sqrt{\frac{7}{3}} < x < 0,0 < x < \sqrt{\frac{7}{3}}

Exercise #9

Solve for X:

lnx+ln(x+1)ln2=3 \ln x+\ln(x+1)-\ln2=3

Video Solution

Answer

1+1+8e32 \frac{-1+\sqrt{1+8e^3}}{2}

Exercise #10

log49x+log4(x+4)log43=ln2e+ln12e \log_49x+\log_4(x+4)-\log_43=\ln2e+\ln\frac{1}{2e}

Find X

Video Solution

Answer

2+393 -2+\frac{\sqrt{39}}{3}

Exercise #11

log5x+log5(x+2)+log25log22.5=log37×log79 \log_5x+\log_5(x+2)+\log_25-\log_22.5=\log_37\times\log_79

Video Solution

Answer

1+6 -1+\sqrt{6}

Exercise #12

Given 0<a , find X:

log2ae7(lna+ln4a)=log4xlog4x2+log41x+1 \log_{2a}e^7(\ln a+\ln4a)=\log_4x-\log_4x^2+\log_4\frac{1}{x+1}

Video Solution

Answer

12+1+4132 -\frac{1}{2}+\frac{\sqrt{1+4^{-13}}}{2}

Exercise #13

logaxlogbylogc2=(logay3logay2)(logb12+logb22)logc(x2+1) \log_ax\log_by\log_c2=(\log_ay^3-\log_ay^2)(\log_b\frac{1}{2}+\log_b2^2)\log_c(x^2+1)

Video Solution

Answer

No solution