SOLUTION: My problem asks to answer the problem in terms of x. 0.75=-2.5log(y/x)

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: My problem asks to answer the problem in terms of x. 0.75=-2.5log(y/x)      Log On


   



Question 821861: My problem asks to answer the problem in terms of x.
0.75=-2.5log(y/x)

Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
Solving an equation for a variable which is in a logarithm usually starts with using algebra and/or properties of logarithms to transform the equation into one of the following general forms:
log(expression) = number
or
log(expression) = log(other_expression)

To get
0.75=-2.5log%28%28y%2Fx%29%29
into the first form, all we need to do is divide both sides by -2.5:
0.75%2F%28-2.5%29+=+log%28%28y%2Fx%29%29
Simplifying the left side we get:
-0.3+=+log%28%28y%2Fx%29%29

The next step with the first form is to rewrite the equation in exponential form. In general log%28a%2C+%28p%29%29+=+n is equivalent to p+=+a%5En. Using this pattern (and the fact that the base of "log" is 10) we get:
10%5E%28-0.3%29+=+y%2Fx
Now that the variables are out of the log we can solve. Since you posted "in terms of x" I'm assuming that we are supposed to solve for y in terms of x. For this we just multiply both sides by x:
10%5E%28-0.3%29%2Ax+=+y
This is an exact expression for y (in terms of x). If we want a decimal approximation, we use our calculators to find that power of 10:
0.5012x+=+y (rounded to 4 places)