Answer
$x \approx 2.961$
Work Step by Step
$\log_2 (2x) + \log_2 (5x-4) = 6$
$\log_2 2x(5x-4) = 6$
$2^{6} = 2x(5x -4)$
$64 = 2x(5x -4)$
$64 = 10x^{2} - 8x$
$10x^{2} - 8x - 64 = 0$
$2(5x^{2} - 4x - 32) = 0$
$x = \frac{-(-4)±\sqrt {(-4)^{2}-4(5)(-32)}}{2(5)}$
$x = \frac{4±\sqrt {16-4(5)(-32)}}{10}$
$x = \frac{4±\sqrt {16+640}}{10}$
$x = \frac{4±\sqrt {656}}{10}$
$x = \frac{4±4\sqrt {41}}{10}$
$x = \frac{2±2\sqrt {41}}{5}$
$x \approx 2.961, -2.161$
$x \approx 2.961$
Since $x$ can't be negative, the only possible solution is $x \approx 2.961$. This is because $\log$ negative a number does not exist and therefore $x$ can only be a positive number in this case.
Check:
$\log_2 (2( \frac{2+2\sqrt {41}}{5})) + \log_2 (5(\frac{2+2\sqrt {41}}{5})-4) \overset{?}{=} 6$
$\log_2 (5.9224...) + \log_2 (10.8062...) \overset{?}{=} 6$
$\log_2 64 \overset{?}{=} 6$
$\log_2 2^{6} \overset{?}{=} 6$
$6\log_2 2 \overset{?}{=} 6$
$6(1) \overset{?}{=} 6$
$ 6 = 6$
