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Mathematics 8 Online
OpenStudy (jiteshmeghwal9):

What is the relation between 'a' & 'b': -

OpenStudy (jiteshmeghwal9):

\[\color{red}{\log_{10}{a}+\log_{10}{b}=\log_{10}{(a+b)}. }\]

OpenStudy (jiteshmeghwal9):

The answer given is \[\color{blue}{a=\frac{b}{b-1}.}\]

mathslover (mathslover):

\[\huge{log(mn)=log_m+log_n}\] \[\huge{a+b=ab}\]

mathslover (mathslover):

can u do it now ?

OpenStudy (lalaly):

correction\[\huge{\log_b (mn)=\log_bm+\log_b n}\]

mathslover (mathslover):

sorry for that mistake @lalaly

OpenStudy (lalaly):

its ok :D

OpenStudy (jiteshmeghwal9):

no:/ I m not getting my answer from this formula actually @mathslover @lalaly

Parth (parthkohli):

lol Lana is never unfair :P

mathslover (mathslover):

wait

OpenStudy (jiteshmeghwal9):

k:)

mathslover (mathslover):

\(\huge{log(a)_{10}=\frac{{log a}}{log10}}\)

OpenStudy (jiteshmeghwal9):

k! i know this:)

OpenStudy (jiteshmeghwal9):

\[\huge{\log_a{10}=\frac{{\log_b{10}}}{\log_b{10}}}\]I think it is like this.

OpenStudy (jiteshmeghwal9):

sorry @ denominator should be "a"

OpenStudy (lalaly):

use the rules of logarithms http://www.sosmath.com/algebra/logs/log4/log44/log44.html when u see a sum of two logs with the same base \[\huge{\log _R U+\log_R V =\log_R (UV)}\]so in ur question u have log a with base 10 and log b with base 10 ... so that is equal to the log of the multiplication of a and b\[\log_{10}a+\log_{10}b=\log_{10}(ab)\] equal that to the two whats given to u \[\log_{10}ab =\log_{10}(a+b) \]and that is equal to \[ab=a+b\]solving for a\[ab-a=b\]\[a(b-1)=b\]\[a=\frac{b}{b-1}\]

OpenStudy (jiteshmeghwal9):

k! thanx a lot @lalaly

OpenStudy (lalaly):

thank @mathslover :D

OpenStudy (jiteshmeghwal9):

xD

mathslover (mathslover):

log^10(a)+log^10(b)=log^10(a+b) Move all the terms containing a logarithm to the left-hand side of the equation. log^10(a)+log^10(b)-log^10(a+b)=0 Combine the logarithmic expressions using the product rule of logarithms. log((a)(b))-log^10(a+b)=0 Combine the logarithmic expressions using the product rule of logarithms. log(((a)(b))/(a+b))=0 Remove the parentheses from the numerator. log((a(b))/(a+b))=0 Multiply a by b in the numerator. log((a*b)/(a+b))=0 Multiply a by b to get ab. log((ab)/(a+b))=0 Let both sides of the equation be the exponent of base 10. 10^(log((ab)/(a+b)))=10^(0) When the base of a logarithm in the exponent and the base of the exponent are the same, the result is the argument of the logarithm. (ab)/(a+b)=10^(0) Any number raised to the power of 0 is 1. (ab)/(a+b)=1 Since the variable is in the denominator on the left-hand side of the equation, this can be solved as a ratio. For example, (A)/(B)=C is equivalent to (A)/(C)=B. (ab)/(1)=(a+b) Dividing any expression by 1 does not change the value of the expression. ab=(a+b) Remove the parentheses around the expression a+b. ab=a+b Since a contains the variable to solve for, move it to the left-hand side of the equation by subtracting a from both sides. ab-a=b Factor out the GCF of a from each term in the polynomial. a(b)+a(-1)=b Factor out the GCF of a from ab-a. a(b-1)=b Divide each term in the equation by (b-1). (a(b-1))/(b-1)=(b)/(b-1) Simplify the left-hand side of the equation by canceling the common terms. a=(b)/(b-1)

mathslover (mathslover):

:D @lalaly

OpenStudy (lalaly):

Wow :D

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