How do I simplify $fraclog_7 32log_7 8cdotsqrt2$?

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So far I have got $log_7 2^5 - log_7 2^3 + log_7 2^1/2$ and am unable to proceed. Am I, on the right track so far? and how do I proceed? thank you!










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  • BTW guys the x is times not 8x sorry!!
    – Negrawh
    Sep 7 at 9:39










  • It is $log_2^3 2^5 cdot sqrt 2$
    – Mohammad Zuhair Khan
    Sep 7 at 9:47










  • Is it $fraclog_732 log_78cdot sqrt2$ ?
    – tarit goswami
    Sep 7 at 9:47










  • Welcome to MathSE. Please read this MathJax tutorial, which explains how to typeset mathematics on this site. It is not clear whether you meant $fraclog_7 32log_7 8 cdot sqrt2$ or $fraclog_7 32log_7 8sqrt2$.
    – N. F. Taussig
    Sep 7 at 9:55










  • @N.F.Taussig I want the second one
    – Negrawh
    Sep 7 at 11:14














up vote
1
down vote

favorite












So far I have got $log_7 2^5 - log_7 2^3 + log_7 2^1/2$ and am unable to proceed. Am I, on the right track so far? and how do I proceed? thank you!










share|cite|improve this question























  • BTW guys the x is times not 8x sorry!!
    – Negrawh
    Sep 7 at 9:39










  • It is $log_2^3 2^5 cdot sqrt 2$
    – Mohammad Zuhair Khan
    Sep 7 at 9:47










  • Is it $fraclog_732 log_78cdot sqrt2$ ?
    – tarit goswami
    Sep 7 at 9:47










  • Welcome to MathSE. Please read this MathJax tutorial, which explains how to typeset mathematics on this site. It is not clear whether you meant $fraclog_7 32log_7 8 cdot sqrt2$ or $fraclog_7 32log_7 8sqrt2$.
    – N. F. Taussig
    Sep 7 at 9:55










  • @N.F.Taussig I want the second one
    – Negrawh
    Sep 7 at 11:14












up vote
1
down vote

favorite









up vote
1
down vote

favorite











So far I have got $log_7 2^5 - log_7 2^3 + log_7 2^1/2$ and am unable to proceed. Am I, on the right track so far? and how do I proceed? thank you!










share|cite|improve this question















So far I have got $log_7 2^5 - log_7 2^3 + log_7 2^1/2$ and am unable to proceed. Am I, on the right track so far? and how do I proceed? thank you!







logarithms






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edited Sep 7 at 11:27









N. F. Taussig

39.7k93153




39.7k93153










asked Sep 7 at 9:39









Negrawh

84




84











  • BTW guys the x is times not 8x sorry!!
    – Negrawh
    Sep 7 at 9:39










  • It is $log_2^3 2^5 cdot sqrt 2$
    – Mohammad Zuhair Khan
    Sep 7 at 9:47










  • Is it $fraclog_732 log_78cdot sqrt2$ ?
    – tarit goswami
    Sep 7 at 9:47










  • Welcome to MathSE. Please read this MathJax tutorial, which explains how to typeset mathematics on this site. It is not clear whether you meant $fraclog_7 32log_7 8 cdot sqrt2$ or $fraclog_7 32log_7 8sqrt2$.
    – N. F. Taussig
    Sep 7 at 9:55










  • @N.F.Taussig I want the second one
    – Negrawh
    Sep 7 at 11:14
















  • BTW guys the x is times not 8x sorry!!
    – Negrawh
    Sep 7 at 9:39










  • It is $log_2^3 2^5 cdot sqrt 2$
    – Mohammad Zuhair Khan
    Sep 7 at 9:47










  • Is it $fraclog_732 log_78cdot sqrt2$ ?
    – tarit goswami
    Sep 7 at 9:47










  • Welcome to MathSE. Please read this MathJax tutorial, which explains how to typeset mathematics on this site. It is not clear whether you meant $fraclog_7 32log_7 8 cdot sqrt2$ or $fraclog_7 32log_7 8sqrt2$.
    – N. F. Taussig
    Sep 7 at 9:55










  • @N.F.Taussig I want the second one
    – Negrawh
    Sep 7 at 11:14















BTW guys the x is times not 8x sorry!!
– Negrawh
Sep 7 at 9:39




BTW guys the x is times not 8x sorry!!
– Negrawh
Sep 7 at 9:39












It is $log_2^3 2^5 cdot sqrt 2$
– Mohammad Zuhair Khan
Sep 7 at 9:47




It is $log_2^3 2^5 cdot sqrt 2$
– Mohammad Zuhair Khan
Sep 7 at 9:47












Is it $fraclog_732 log_78cdot sqrt2$ ?
– tarit goswami
Sep 7 at 9:47




Is it $fraclog_732 log_78cdot sqrt2$ ?
– tarit goswami
Sep 7 at 9:47












Welcome to MathSE. Please read this MathJax tutorial, which explains how to typeset mathematics on this site. It is not clear whether you meant $fraclog_7 32log_7 8 cdot sqrt2$ or $fraclog_7 32log_7 8sqrt2$.
– N. F. Taussig
Sep 7 at 9:55




Welcome to MathSE. Please read this MathJax tutorial, which explains how to typeset mathematics on this site. It is not clear whether you meant $fraclog_7 32log_7 8 cdot sqrt2$ or $fraclog_7 32log_7 8sqrt2$.
– N. F. Taussig
Sep 7 at 9:55












@N.F.Taussig I want the second one
– Negrawh
Sep 7 at 11:14




@N.F.Taussig I want the second one
– Negrawh
Sep 7 at 11:14










2 Answers
2






active

oldest

votes

















up vote
3
down vote



accepted










Your expansion is not correct. If $b, x, y > 0$, with $b neq 1$, then
beginalign*
log_b (xy) & = log_b x + log_b y\
log_b left(fracxyright) & = log_b x - log_b y
endalign*
However, you have
$$fraclog_7 32log_7 8sqrt2$$
which is a quotient of logarithms, not the logarithm of a quotient, so you cannot apply those rules here.



However, your observations that $32 = 2^5$, $8 = 2^3$, and $sqrt2 = 2^1/2$ would be useful if we were working with logarithms to the base $2$. To do so, we use the Change of Base Formula. Let $a, b, x > 0$, with $a, b neq 1$. Then
$$log_a x = fraclog_b xlog_b a$$
By setting $a = 7$ and $b = 2$, we obtain
beginalign*
fraclog_7 32log_7 8sqrt2 & = fracdfraclog_2 32log_2 7dfraclog_2 8sqrt2log_2 7\
& = fraclog_2 32log_2 8sqrt2\
& = fraclog_2 2^5log_2 2^32^1/2\
& = frac5log_2 2^7/2\
& = frac5frac72\
& = frac107
endalign*






share|cite|improve this answer




















  • Thanks for pointing out my mistake and very helpful!
    – Negrawh
    Sep 8 at 11:30

















up vote
2
down vote













You can use the formula



$$fraclog_ablog_ac=log_cb$$
$$fraclog_732log_78cdot sqrt2=left(log_832right)cdot sqrt2=frac5sqrt23$$



Or If you are looking for this



$$fraclog_732log_78sqrt2 =left(log_8sqrt232right)=frac5frac72=frac107$$






share|cite|improve this answer






















  • Thank you !!!!!
    – Negrawh
    Sep 8 at 11:30










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2 Answers
2






active

oldest

votes








2 Answers
2






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
3
down vote



accepted










Your expansion is not correct. If $b, x, y > 0$, with $b neq 1$, then
beginalign*
log_b (xy) & = log_b x + log_b y\
log_b left(fracxyright) & = log_b x - log_b y
endalign*
However, you have
$$fraclog_7 32log_7 8sqrt2$$
which is a quotient of logarithms, not the logarithm of a quotient, so you cannot apply those rules here.



However, your observations that $32 = 2^5$, $8 = 2^3$, and $sqrt2 = 2^1/2$ would be useful if we were working with logarithms to the base $2$. To do so, we use the Change of Base Formula. Let $a, b, x > 0$, with $a, b neq 1$. Then
$$log_a x = fraclog_b xlog_b a$$
By setting $a = 7$ and $b = 2$, we obtain
beginalign*
fraclog_7 32log_7 8sqrt2 & = fracdfraclog_2 32log_2 7dfraclog_2 8sqrt2log_2 7\
& = fraclog_2 32log_2 8sqrt2\
& = fraclog_2 2^5log_2 2^32^1/2\
& = frac5log_2 2^7/2\
& = frac5frac72\
& = frac107
endalign*






share|cite|improve this answer




















  • Thanks for pointing out my mistake and very helpful!
    – Negrawh
    Sep 8 at 11:30














up vote
3
down vote



accepted










Your expansion is not correct. If $b, x, y > 0$, with $b neq 1$, then
beginalign*
log_b (xy) & = log_b x + log_b y\
log_b left(fracxyright) & = log_b x - log_b y
endalign*
However, you have
$$fraclog_7 32log_7 8sqrt2$$
which is a quotient of logarithms, not the logarithm of a quotient, so you cannot apply those rules here.



However, your observations that $32 = 2^5$, $8 = 2^3$, and $sqrt2 = 2^1/2$ would be useful if we were working with logarithms to the base $2$. To do so, we use the Change of Base Formula. Let $a, b, x > 0$, with $a, b neq 1$. Then
$$log_a x = fraclog_b xlog_b a$$
By setting $a = 7$ and $b = 2$, we obtain
beginalign*
fraclog_7 32log_7 8sqrt2 & = fracdfraclog_2 32log_2 7dfraclog_2 8sqrt2log_2 7\
& = fraclog_2 32log_2 8sqrt2\
& = fraclog_2 2^5log_2 2^32^1/2\
& = frac5log_2 2^7/2\
& = frac5frac72\
& = frac107
endalign*






share|cite|improve this answer




















  • Thanks for pointing out my mistake and very helpful!
    – Negrawh
    Sep 8 at 11:30












up vote
3
down vote



accepted







up vote
3
down vote



accepted






Your expansion is not correct. If $b, x, y > 0$, with $b neq 1$, then
beginalign*
log_b (xy) & = log_b x + log_b y\
log_b left(fracxyright) & = log_b x - log_b y
endalign*
However, you have
$$fraclog_7 32log_7 8sqrt2$$
which is a quotient of logarithms, not the logarithm of a quotient, so you cannot apply those rules here.



However, your observations that $32 = 2^5$, $8 = 2^3$, and $sqrt2 = 2^1/2$ would be useful if we were working with logarithms to the base $2$. To do so, we use the Change of Base Formula. Let $a, b, x > 0$, with $a, b neq 1$. Then
$$log_a x = fraclog_b xlog_b a$$
By setting $a = 7$ and $b = 2$, we obtain
beginalign*
fraclog_7 32log_7 8sqrt2 & = fracdfraclog_2 32log_2 7dfraclog_2 8sqrt2log_2 7\
& = fraclog_2 32log_2 8sqrt2\
& = fraclog_2 2^5log_2 2^32^1/2\
& = frac5log_2 2^7/2\
& = frac5frac72\
& = frac107
endalign*






share|cite|improve this answer












Your expansion is not correct. If $b, x, y > 0$, with $b neq 1$, then
beginalign*
log_b (xy) & = log_b x + log_b y\
log_b left(fracxyright) & = log_b x - log_b y
endalign*
However, you have
$$fraclog_7 32log_7 8sqrt2$$
which is a quotient of logarithms, not the logarithm of a quotient, so you cannot apply those rules here.



However, your observations that $32 = 2^5$, $8 = 2^3$, and $sqrt2 = 2^1/2$ would be useful if we were working with logarithms to the base $2$. To do so, we use the Change of Base Formula. Let $a, b, x > 0$, with $a, b neq 1$. Then
$$log_a x = fraclog_b xlog_b a$$
By setting $a = 7$ and $b = 2$, we obtain
beginalign*
fraclog_7 32log_7 8sqrt2 & = fracdfraclog_2 32log_2 7dfraclog_2 8sqrt2log_2 7\
& = fraclog_2 32log_2 8sqrt2\
& = fraclog_2 2^5log_2 2^32^1/2\
& = frac5log_2 2^7/2\
& = frac5frac72\
& = frac107
endalign*







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Sep 7 at 13:53









N. F. Taussig

39.7k93153




39.7k93153











  • Thanks for pointing out my mistake and very helpful!
    – Negrawh
    Sep 8 at 11:30
















  • Thanks for pointing out my mistake and very helpful!
    – Negrawh
    Sep 8 at 11:30















Thanks for pointing out my mistake and very helpful!
– Negrawh
Sep 8 at 11:30




Thanks for pointing out my mistake and very helpful!
– Negrawh
Sep 8 at 11:30










up vote
2
down vote













You can use the formula



$$fraclog_ablog_ac=log_cb$$
$$fraclog_732log_78cdot sqrt2=left(log_832right)cdot sqrt2=frac5sqrt23$$



Or If you are looking for this



$$fraclog_732log_78sqrt2 =left(log_8sqrt232right)=frac5frac72=frac107$$






share|cite|improve this answer






















  • Thank you !!!!!
    – Negrawh
    Sep 8 at 11:30














up vote
2
down vote













You can use the formula



$$fraclog_ablog_ac=log_cb$$
$$fraclog_732log_78cdot sqrt2=left(log_832right)cdot sqrt2=frac5sqrt23$$



Or If you are looking for this



$$fraclog_732log_78sqrt2 =left(log_8sqrt232right)=frac5frac72=frac107$$






share|cite|improve this answer






















  • Thank you !!!!!
    – Negrawh
    Sep 8 at 11:30












up vote
2
down vote










up vote
2
down vote









You can use the formula



$$fraclog_ablog_ac=log_cb$$
$$fraclog_732log_78cdot sqrt2=left(log_832right)cdot sqrt2=frac5sqrt23$$



Or If you are looking for this



$$fraclog_732log_78sqrt2 =left(log_8sqrt232right)=frac5frac72=frac107$$






share|cite|improve this answer














You can use the formula



$$fraclog_ablog_ac=log_cb$$
$$fraclog_732log_78cdot sqrt2=left(log_832right)cdot sqrt2=frac5sqrt23$$



Or If you are looking for this



$$fraclog_732log_78sqrt2 =left(log_8sqrt232right)=frac5frac72=frac107$$







share|cite|improve this answer














share|cite|improve this answer



share|cite|improve this answer








edited Sep 7 at 10:05

























answered Sep 7 at 9:47









Deepesh Meena

4,0162925




4,0162925











  • Thank you !!!!!
    – Negrawh
    Sep 8 at 11:30
















  • Thank you !!!!!
    – Negrawh
    Sep 8 at 11:30















Thank you !!!!!
– Negrawh
Sep 8 at 11:30




Thank you !!!!!
– Negrawh
Sep 8 at 11:30

















 

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