a) 5x = 125
\(\Rightarrow\)5x = 53
\(\Rightarrow\)x = 3
b, 32x = 81
\(\Rightarrow\)32x = 34
\(\Rightarrow\)2x = 4
\(\Rightarrow\) x = 4 : 2
\(\Rightarrow\) x = 2
c, 52x-3 - 2 . 52 = 52 . 3
52x-3 - 2 . 25 = 25 . 3
52x-3 - 50 = 75
52x-3 = 75 + 50
52x-3 = 125
52x-3 = 53
2x - 3 = 3
2x = 3 + 3
2x = 6
x = 6 : 2
x = 3
a, 5x = 125 suy ra 5x = 53 suy ra x = 3
b, 32x = 81 suy ra 32x = 34 suy ra x = 2
c, 52x - 3 - 2.52 = 52 . 3
suy ra 52x : 53 = 52 .3 + 2. 52
suy ra 52x : 53 = 52 . 5
suy ra 52x = 53 . 52 . 53
52x = 56 suy ra 2x = 6 suy ra x = 3
a) \(5^x\)= 125
\(\Leftrightarrow\)\(5^x\)= \(5^3\)\(\Rightarrow\)x = 3
b) \(3^{2x}\)= 81
\(\Leftrightarrow\)\(3^{2x}\)= \(3^4\)\(\Rightarrow\)\(2\)x = \(4\) \(\Rightarrow\)x = \(\frac{4}{2}\)= \(2\)
c) \(5^{2x-3}\)- \(2\) . \(5^2\)= \(5^2\). \(3\)
\(\Rightarrow\)\(5^{2x}\): \(5^3\)- \(2\) . \(5^2\)= \(5^2\). \(3\)
\(\Rightarrow\)\(5^{2x}\): \(5^3\)= \(5^2\). \(3\) + \(5^2\). \(2\)
\(\Rightarrow\)\(5^{2x}\): \(5^3\)= \(5^2\). \(\left(3+2\right)\)
\(\Rightarrow\)\(5^{2x}\): \(5^3\)= \(5^2\). \(5\)= \(5^3\)
\(\Rightarrow\)\(5^{2x}\)= \(5^3\). \(5^3\)= \(5^6\)
\(\Rightarrow\)\(2x\)= \(6\)
\(\Rightarrow\)\(x\)= \(\frac{6}{2}\)= \(3\)
