(1) 40^(x-1)=2^(2*x+1) . Standard reception . if both parts of the equation are positive , and the unknown only in the indicators of the degree , we equate the left and right logarithms . We get : (2) (x-1)*lg(40)=(2*x+1)*lg(2) . { lg(40)=lg(10)+lg(4)=1+2*a (a=lg(2) ) }. We get : (2.1) (x-1)*(1+2*a)=a*(2*x+1). We get your answer. With respect. Lidiy
@@ЕленаПотапова-в8щ of course a logarithm must have a base, and that base can indeed be any number, and we generally indicate this number in subscript next to "log". However, "log" without a base specified has come to be a shorthand for "log base 10" most commonly, at least in all the textbooks and other media I have consumed.
@@ЕленаПотапова-в8щ some people use log to mean base 10 and lg to mean base 2; even if you believe that that is incorrect, common usage should be considered. Outside of the context of computer science or high level maths, log(x) usually means base 10.
(1) 40^(x-1)=2^(2*x+1) . Standard reception . if both parts of the equation are positive , and the unknown only in the indicators of the degree , we equate the left and right logarithms . We get : (2) (x-1)*lg(40)=(2*x+1)*lg(2) . { lg(40)=lg(10)+lg(4)=1+2*a (a=lg(2) ) }. We get : (2.1) (x-1)*(1+2*a)=a*(2*x+1). We get your answer.
With respect. Lidiy
40^x= 80x 4^x
10^x-=80
X=log80
X=1.9031
I failed to solve this one on my own before I watched your solution. I learned a lot from your solution and enjoyed the video!
Почему основание логарифма не пишет?
"log" on its own is commonly used to mean "log base 10"
@@resr35m нет, есть lg по основанию 10, (значков не таких чтобы показать) есть log по основанию 2 и т. д. ln по основанию e. Что за правила у вас?
@@ЕленаПотапова-в8щ of course a logarithm must have a base, and that base can indeed be any number, and we generally indicate this number in subscript next to "log". However, "log" without a base specified has come to be a shorthand for "log base 10" most commonly, at least in all the textbooks and other media I have consumed.
@@resr35m lgx вот это и есть по основанию 10
@@ЕленаПотапова-в8щ some people use log to mean base 10 and lg to mean base 2; even if you believe that that is incorrect, common usage should be considered. Outside of the context of computer science or high level maths, log(x) usually means base 10.