Question

tính giá trị biểu thức

a) \(\log_2\dfrac{2}{3}+\log_212\)

b) \(\log_228-\log_27\)

c) \(\log_327\)

d) \(\log_{32}2\)

f) \(\log_381\)

Answer 1

\(log_2\dfrac{2}{3}+log_212=log_2\left(\dfrac{2}{3}.12\right)=log_28=3\)

\(log_228-log_27=log_2\left(\dfrac{28}{7}\right)=log_24=2\)

\(log_327=log_33^3=3log_33=3\)

\(log_{32}2=log_{2^5}2=\dfrac{1}{5}log_22=\dfrac{1}{5}\)

\(log_381=log_33^4=4log_33=4\)

Answer 2

a) \(\log_2\dfrac{2}{3}+log_212=log_2\left(\dfrac{2}{3}.12\right)=log_28=3\)

b) \(log_228-log_27=log_2\left(\dfrac{28}{7}\right)=log_24=2\)

c) \(log_327=log_3\left(3^3\right)=3\)

d) \(log_{32}2=log_{2^5}2=\dfrac{1}{5}\)

e) \(log_381=log_3\left(3^4\right)=4\)