222k views
3 votes
NO LINKS!
Please help me​

NO LINKS! Please help me​-example-1

2 Answers

4 votes

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

User Adi H
by
8.9k points
4 votes

Answer:

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.)

User GAgnew
by
8.0k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories