Question

NO LINKS!
Please help me​

Answer 1

Answer: B) Not enough information

Reason:

If we were asked to compute log(ab), then we could use this log rule

log(ab) = log(a) + log(b)

However, we aren't multiplying the 'a' and b, so we cannot use the log rule above. There's not enough information to be able to compute log(a+b)

Choice C is a trick answer I've seen many students fall for since the erroneous thinking would be log(a+b) = log(a)+log(b) = 1.2+5.6 = 6.8

Answer 2

b) Not enough information

Explanation:

Given the logs of two values, you want to know the log of their sum.

Rules of logarithms

The logarithm function cannot be applied to a sum. The purpose of the logarithm function is to turn the log of a product into a sum of logs. The logarithm function cannot be applied to a sum.

The only way to determine the log of the sum is to take the antilogs of the given values, add them, then take the log of the result.

Log(a+b)

Assuming the base of the logarithms is 10, using the strategy just described, we can compute ...

log(a +b) = log(10^log(a) +10^log(b)) = log(10^1.2 +10^5.6)

≈ log(15.848932 +398,107.17) ≈ log(398,123.02)

≈ 5.6000173 . . . . using base 10 logs

If these are natural logs, which are also often written as log(x), as well as ln(x), then the log of the sum is about

log(e^1.2 +e^5.6) ≈ 5.6122026 . . . . using base e logs

The short answer is, there is not enough information. (The base of the logarithms must be known.)