Unknown Problem

Algebra Level 2

Solve the following equation for v v :

log v + log 5 = 3 \large\log v+\log 5 = 3 .

Note: log \log is the common logarithm, i.e., base 10 10 .


The answer is 200.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

4 solutions

Noah Smalls
Feb 1, 2017

Look at the given equation:

1.log v+log 5=3 Use the Product Property to combine the logarithms. log 5 v=3 Rewrite this as an exponential equation and solve for v.

2.log 5 v = 3 5 v = 103 5 v = 1,000 v = 200 Divide both sides by 5

3.The solution is valid only if the original equation makes sense when v is 200. In other words, the expression inside the logarithm in the original equation must be positive. log v+log 5 = 3 log 200+log 5 = 3 Plug in the solution, v=200 The expressions inside the logarithms are 5 and 200, which are positive. This means the logarithms in the original equation are well defined. So, v=200 is a valid solution.

Nashita Rahman
Feb 3, 2017

log 10 v + log 10 5 \log_{10}v + \log_{10}5 = 1+1+1

log 10 v + log 10 5 \log_{10}v + \log_{10}5 = log 10 10 + log 10 10 + log 10 10 \log_{10}10 + \log_{10}10 + \log_{10}10 (since log 10 10 \log_{10}10 = 1)

log 10 ( 5 v ) = log 10 1000 \log_{10}(5v) = \log_{10}1000 (since log a + log b = log (ab) )

5v =1000

v=200

Betty BellaItalia
Apr 17, 2017

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...