a)\(5^x=125\)
\(\Rightarrow5^x=5^3\Rightarrow x=3\)
b)\(3^{2x}=81\)
\(\Rightarrow3^{2x}=3^4\)
\(\Rightarrow2x=4\Rightarrow x=2\)
c)\(5^{2x-3}-2\cdot5^2=5^2\cdot3\)
\(\Rightarrow5^{2x-3}-2\cdot25=25\cdot3\)
\(\Rightarrow5^{2x-3}-50=75\)
\(\Rightarrow5^{2x-3}=125\)
\(\Rightarrow5^{2x-3}=5^3\)
\(\Rightarrow2x-3=3\)
\(\Rightarrow2x=6\Rightarrow x=3\)
a) \(5^x=125\)
\(5^x=5^3\)
\(=>x=3\)
b) \(3^{2x}=81\)
\(3^{2x}=3^4\)
\(3^x=3^{4:2}\)
\(3^x=3^2\)
\(=>x=2\)
c) \(5^{2x-3}-2.5^2=5^2.3\)
\(5^{2x}-2.25=25.3\)
\(5^{2x}-50=75\)
\(5^{2x}\) \(=75+50\)
\(5^{2x}\) \(=125\)
\(5^{2x}\) \(=5^3\)
\(5^x\) \(=5^{3 :2}\)
\(5^x\) \(=5^{1,5}\)
\(=>x=1,5\)
d) \(\left|x\right|< 5\)
\(=>x\) thuộc \(\left\{4;3;2;1;0;-1;-2;-3;-4\right\}\)
a) 5x=125
=>5x=53
=>x=3
vậy...
b) 32x=81
=>32x=34
=>2x=4
=>x=2
Vậy...
c) 52x-3-2.52=52.3
=>52x-3-2.25=25.3
=>52x-3-50=75
=>52x-3=125
=>52x-3=53
=>2x-3=3
=>2x=6
=>x=3
\(\left|x\right|< 5\)
=>\(\left|x\right|\in\left\{1;2;3;4\right\}\)
=>\(x\in\left\{-4;-3;-2;-1;0;1;2;3;4\right\}\)