To establish that \( \log(10^7\cdot 5) = 7 + \log 5 \), the first step is to rewrite the expression by moving the exponent in front of the logarithm. Therefore, the correct response is:
The first step is to move the exponent in front of the logarithm, such that \( \log(10^7\cdot 5) = 7 + \log(5) \).
This is because of the logarithmic identity \( \log(a \cdot b) = \log a + \log b \) and the property \( \log(a^n) = n \cdot \log(a) \).