Question

What is the exact value of x?

Answer 1

Answer:

B

Step-by-step explanation:

$5\cdot 21^{5x} = 16 \\\ 21^{5x} = \frac{16}{5} \\\\ 21^{5x} = 3.2 \\\ log 21^{5x} = log 3.2 \\\ 5x\cdot log 21 = log 3.2 \\\ 5x = \frac{log 3.2}{log 21} \\\\\ x = \frac{log 3.2}{5\cdot log 21}$

I hope I helped you.