a) \(2^x-15=17\)
\(2^x=17+15\)
\(2^x=32\)
\(\Rightarrow2^x=2^5\)
\(\Rightarrow x=5\)
b) \(27.3^x=243\)
\(3^x=243:27\)
\(3^x=9\)
\(\Rightarrow3^x=3^2\)
\(\Rightarrow x=2\)
c) \(3^x+25=26.2^2+2.3^0\)
\(3^x+25=104+2\)
\(3^x+25=106\)
\(3^x=106-25\)
\(3^x=81\)
\(\Rightarrow3^x=3^4\)
\(\Rightarrow x=4\)
d) \(\left(7x-11\right)^3=2^5.5^2+200\)
\(\left(7x-11\right)^3=800+200\)
\(\left(7x-11\right)^3=1000\)
\(\Rightarrow\left(7x-11\right)^3=10^3\)
\(\Rightarrow7x-11=10\)
\(7x=10+11\)
\(7x=21\)
\(x=21:7\)
\(x=3\)
e) \(3^x.3=27\)
\(3^x=27:3\)
\(3^x=9\)
\(\Rightarrow3^x=3^2\)
\(\Rightarrow x=2\)
a) \(2^x-15=17\)
\(\Leftrightarrow2^x=17+15\)
\(\Leftrightarrow2^x=32\)
\(\Leftrightarrow2^x=2^5\)
\(\Leftrightarrow x=5\)
Vậy x = 5
b) \(27.3^x=243\)
\(\Leftrightarrow3^x=243:27\)
\(\Leftrightarrow3^x=9\)
\(\Leftrightarrow3^x=3^2\)
\(\Leftrightarrow x=2\)
Vậy x = 2
c) \(\left(7x-11\right)^3=2^5.5^2+200\)
\(\Leftrightarrow\left(7x-11\right)^3=800+200\)
\(\Leftrightarrow\left(7x-11\right)^3=1000\)
\(\Leftrightarrow\left(7x-11\right)^3=10^3\)
\(\Leftrightarrow7x-11=10\)
\(\Leftrightarrow7x=10+11\)
\(\Leftrightarrow7x=21\)
\(\Leftrightarrow x=21:7\)
\(\Leftrightarrow x=3\)
Vậy x = 3
d) \(3^x.3=27\)
\(\Leftrightarrow3^x=27:3\)
\(\Leftrightarrow3^x=9\)
\(\Leftrightarrow3^x=3^2\)
\(\Leftrightarrow x=2\)
Vậy x = 2
_Chúc bạn học tốt_
