xLeeChaex 46 Posted December 6, 2014 Share Posted December 6, 2014 I need help with logarithmic equations and it says to solve each one. Then it says to express irrational solutions in exact form and as a decimal rounded to three decimal places. 9. log 4 base (x+2) = log 4 base 8 log (x+2)=8 x+2=8 x=6 This is how u solve it the proper way right?? lol It does say on my book that answer is 6 but i just wanna make sure it was solved properly. 12. -2log 4 base X= log 4 base 9 x^-2=9 √1/x^2=9 ^Im not sure how to solve this because idk what else to do? Is the answer 1/3?? lol 15 3log 2 base (x-1) + log 2 base 4=5 This is how i solved it (x-1)^3 +4=2^5 and then u have to do the whole factoring thing i believe lol which leads me to x^3-3x^2+3x-1+4=32 x^3-3x^2+3x-29=0 But the solution was wrong, it says it was 3 but idk how.... Can u guys pleasseeeeeeee help i really need to learn these bc my teacher taught this on the last minute and its on the final test lol Link to comment Share on other sites More sharing options...
harootony 5,523 Posted December 6, 2014 Share Posted December 6, 2014 I got 0% in my logarithmic test, sorry can't help Link to comment Share on other sites More sharing options...
Silktiger 3,227 Posted December 6, 2014 Share Posted December 6, 2014 #12 -2log4x=log49 4-2log4x=4log49 Exponents are multiplied when you raise it to a power, so like 4-2log4x is equal to (4log4x)-2 (4log4x)-2=4log49 Take care of the (4log4x)-2. That equals (x)-2, which can also be written as 1/x2 1/x2=9 1=9x2 x2=1/9 x= plus or minus 1/3 (not sure about the plus or minus but I think there is one) #15 3log2(x-1)+log24=5 So log24=2 3log2(x-1)+2=5 3log2(x-1)=3 log2(x-1)=1 2log2(x-1)=21 x-1=2 x=3 Link to comment Share on other sites More sharing options...
xLeeChaex 46 Posted December 6, 2014 Author Share Posted December 6, 2014 Wait for #12, is it -2log4x=log49 for the original equation? Yes!! Link to comment Share on other sites More sharing options...
xLeeChaex 46 Posted December 6, 2014 Author Share Posted December 6, 2014 #12 -2log4x=log49 4-2log4x=4log49 Exponents are multiplied when you raise it to a power, so like 4-2log4x is equal to (4log4x)-2 (4log4x)-2=4log49 Take care of the (4log4x)-2. That equals (x)-2, which can also be written as 1/x2 1/x2=9 1=9x2 x2=1/9 x= plus or minus 1/3 (not sure about the plus or minus but I think there is one) #15 3log2(x-1)+log24=5 So log24=2 3log2(x-1)+2=5 3log2(x-1)=3 log2(x-1)=1 2log2(x-1)=21 x-1=2 x=3 How did u get rid of the 3 infront of the log when i thought u put it like this 3^3 for 3log 2 base (x-1)=3 Link to comment Share on other sites More sharing options...
Silktiger 3,227 Posted December 6, 2014 Share Posted December 6, 2014 How did u get rid of the 3 infront of the log when i thought u put it like this 3^3 for 3log 2 base (x-1)=3 3log2(x-1) naw that's just 3 x log2(x-1) so I just divided it out so that's why the 3 on the other side became a 1 Link to comment Share on other sites More sharing options...
Taelent 9,485 Posted December 6, 2014 Share Posted December 6, 2014 For 12 yes the answer is 1/3, except I'm not sure why there is a square root on the 1 (it equals to 1 anyway, but yeah) edit: and I just picked up on something - for logs like , the base is actually 4, not (x+2) Link to comment Share on other sites More sharing options...
xLeeChaex 46 Posted December 6, 2014 Author Share Posted December 6, 2014 3log2(x-1) naw that's just 3 x log2(x-1) so I just divided it out so that's why the 3 on the other side became a 1 Ohh i see it now lol And did i do number 9 correct lol?? and i need help with number 13, can u help at least lol 3log 2 base x=-log 2 base 27 this is how i solved it log 2 base x^3 = 27^-1 x^3=1/27 x=1/3 Like how do u solved the part where it says x^3=1/27?? lol im only good with x^2 if it was put that way XD Link to comment Share on other sites More sharing options...
Taelent 9,485 Posted December 6, 2014 Share Posted December 6, 2014 Ohh i see it now lol And did i do number 9 correct lol?? and i need help with number 13, can u help at least lol 3log 2 base x=-log 2 base 27 this is how i solved it log 2 base x^3 = 27^-1 x^3=1/27 x=1/3 Like how do u solved the part where it says x^3=1/27?? lol im only good with x^2 if it was put that way XD Link to comment Share on other sites More sharing options...
!~Aishak~! 1,813 Posted December 6, 2014 Share Posted December 6, 2014 why don't u try my way .. it is my secret way lolz.. u might find it weird just i mistook the no.#12 i meant in the end x=1/3 not x^2=1/3 Link to comment Share on other sites More sharing options...
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