Find the real number x satisfying \[\log_{1/2} (2x + 1 ) <-3\]?
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OpenStudy (anonymous):
this type was done by @satellite73 yesterday but am confused
OpenStudy (anonymous):
@satellite73 can u help me out
OpenStudy (anonymous):
yes lets change the base to make life easier
OpenStudy (anonymous):
\[\log_{\frac{1}{2}}(x)=-\log_2(x)\]
OpenStudy (anonymous):
ok
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OpenStudy (anonymous):
if that is not clear, lets show it
by the change of base formula we know
\[\log_{\frac{1}{2}}(x)=\frac{\log_2(x)}{\log_2(\frac{1}{2})}=\frac{\log_2(x)}{-1}=-\log_2(x)\]
OpenStudy (anonymous):
site is stuck
OpenStudy (anonymous):
ok now we can solve
\[-\log_2(2x+1)<-3\] easily
change the signs and the sense of the inequality and get
\[\log_2(2x+1)>3\]
OpenStudy (anonymous):
since log base 2 is an increasing function we conclude that
\[2x+1>2^3\]
\[2x+1>8\] and solve that one
OpenStudy (anonymous):
2x+1=8 x=7/2 is it....
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OpenStudy (anonymous):
it is an inequality, not an equality
OpenStudy (anonymous):
\(x>\frac{7}{2}\)
OpenStudy (anonymous):
sorry
OpenStudy (anonymous):
hope steps were clear
OpenStudy (anonymous):
hey wat is the difference between the yesterdays question and todyss can u tell plz
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